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By Authority Of 

THE UNITED STATES OF AMERICA 

Legally Binding Document 



By the Authority Vested By Part 5 of the United States Code § 552(a) and 
Part 1 of the Code of Regulations § 51 the attached document has been duly 
INCORPORATED BY REFERENCE and shall be considered legally 
binding upon all citizens and residents of the United States of America. 
HEED THIS NOTICE : Criminal penalties may apply for noncompliance. 




Document Name: IEEE 112: Test Procedure for Polyphase Induction Motors 

and Generators 

CFR Section(s): 10 CFR 431.15 



Standards Body: Institute of Electrical and Electronics Engineers 



■1 



illllli 



IEEEStd112™-2004 

(Revision of 
lEEEStd 112-1996) 



112™ 

IEEE Standard Test Procedure for 
Polyphase Induction Motors and 
Generators 



■b 



IEEE Power Engineering Society 

Sponsored by the 

Electric Machinery Committee 



I :■ I 

111 :"""'B 

II mk 



Will 

mm 




3 Park Avenue, New York, NY 10016-5997, USA 



4 November 2004 

Print: SH95211 
PDF: SS95211 



Recognized as an IEEE Std 1 1 2™-2004 

American National Standard (ANSI) (Revision of 

IEEE Std 112-1996) 



IEEE Standard Test Procedure for 
Polyphase Induction Motors and 
Generators 



Sponsor 

Electric Machinery Committee 

of the 

IEEE Power Engineering Society 



Approved 12 May 2004 

American National Standard Institute 

Approved 9 February 2004 
IEEE-SA Standards Board 



Abstract: instructions for conducting and reporting the more generally applicable and acceptable 

tests of polyphase induction motors and generators are covered. 

Keywords: acceptance and performance testing, generators, induction, machines, motors, 

polyphase 



The Institute of Electrical and Electronics Engineers, inc. 
3 Park Avenue, New York, NY 10016-5997, USA 

Copyright © 2004 by the institute of Electrical and Electronics Engineers, Inc. 

All rights reserved. Published 4 November 2004. Printed in the United States of America. 

IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics 
Engineers, Incorporated. 

Print: ISBN 0-7381-3977-7 SH95211 
PDF: ISBN 0-7381-3978-5 SS9521 1 

No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior 
written permission of the publisher. 



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Introduction 



This introduction is not part of IEEE Std 112-2004, IEEE Standard Test Procedure for Polyphase 
Induction Motors and Generators. 



This standard provides the basic test procedure for evaluating the performance of a polyphase induction 
motor or generator of any size. Each revision of the standard since its 1964 introduction as an IEEE standard 
has been to keep the standard current with improvements in instrumentation, with improvements in test tech- 
niques, with increased knowledge in the art of measurements, and with the constant change in the needs and 
desires of the machine users and of those concerned with energy conservation and the like. Major portions of 
the document have been rearranged to accomplish this and the user is cautioned to check any external refer- 
ences to particular clauses of previous versions tor the correct clause number in this version. Each individual 
test is defined and each efficiency test method is now covered in more detail and step-by-step instructions 
are presented. Standard symbols are now used for all quantities. 

Notice to users 

Errata 

Errata, if any, for this and all other standards can be accessed at the following URL: http:// 
standards.ieee.org/reading/ieee/updates/errata/mdex.html. Users are encouraged to check this URL for 
errata periodically. 

Interpretations 

Current interpretations can be accessed at the following URL: http://standards.ieee.org/reading/ieee/inteip/ 
index .html. 

Patents 

Attention is called to the possibility that implementation of this standard may require use of subject matter 
covered by patent rights. By publication of this standard, no position is taken with respect to the existence or 
validity of any patent rights in connection therewith. The IEEE shall not be responsible for identifying 
patents or patent applications for which a license may be required to implement an IEEE standard or for 
conducting inquiries into the legal validity or scope of those patents that are brought to its attention. 



Copyright© 2004 IEEE. AN rights reserved. 



Participants 



The following is a list of the participants of the Electric Machinery Committee Working Group on this 
standard: 



Paul Anderson 
Robert Bartheld (Liaison) 
Paul G Cummings 
Roger H. Daugherty 
James H. Dymond 



Franklin H. Grooms, Chair 

Nirmal K. Ghai 
John S. Hsu 
Khursheed S. Hussein 
Ziba Kellum 



Joseph Kline 
Bill Lockley 
Walter!. Martiny 
Venkatachari Rajagopalan 
Steven J. Stretz 



The following members of the individual balloting committee voted on this standard. Balloters may have 
voted for approval, disapproval, or abstention. 



Paul Anderson 
William Bartley 
Thomas Bishop 
Thomas Blair 
Steven Brockschink 
Weijen Chen 
Tommy Cooper 
Mike Darby 
Roger Daugherty 
Byron Davenport 
Gary Donner 
James H. Dymond 
James H. Edmonds 
Ahmed El-Serafi 
Amir El-Sheikh 
Gary Engmann 



Jorge Fernandez-Daher 
Trilok Garg 
Nirmal K. Ghai 
Franklin H. Grooms 
Randall Groves 
Bal Gupta 
Paul Hamer 
Gary Heuston 
Ajit Hiranandani 
Edward Morgan Jr. 
George Kalacherry 
Yuri Khersonsky 
Geoff Klempner 
Joseph Kline 
Roger Lawrence 
Timothy Lensmire 



Lisardo Lourido 

Antonio J. Marques-Cardoso 

Jesus Martinez 

Walter J. Martiny 

Thomas McCaffrey 

Nigel McQuin 

James Michalec 

Gary Michel 

Krste Najdenkoski 

Arthur Neubauer 

Nils Nilsson 

Alvaro Portillo 

Mad an Rana 

James Ruggieri 

Greg Stone 

Shanmugan Thamilarasan 



When the IEEE-SA Standards 
membership: 



Chuck Adams 
H. Stephen Berger 
Mark D. Bowman 
Joseph A. Bruder 
Bob Davis 
Roberto de Boisson 
Julian Forster* 
Arnold M. Greenspan 



Board approved this standard on 9 February 2004, it had the following 



Don Wright, Chair 
vacant, Vice Chair 
Judith Gorman, Secretary 
Mark S. Halpin 
Raymond Hapeman 
Richard J. Holleman 
Richard H. Hulett 
Lowell G. Johnson 
Joseph L. Koepfinger* 
Hermann Koch 
Thomas J. McGean 



Daleep C. Mohla 
Paul Nikolich 
T. W. Olsen 
Ronald C. Petersen 
Gary S. Robinson 
Frank Stone 
Malcolm V. Thaden 
Doug Topping 
Joe D. Watson 



^Member Emeritus 



Also included are the following nonvoting IEEE-SA Standards Board liaisons: 

Satish K. Aggarwal, NRC Representative 

Richard DeBlasio, DOE Representative 

Alan Cookson, NIST Representative 



Don Messina 
IEEE Standards Project Editor 



Copyright © 2004 IEEE. All rights reserved. 



Contents 

1. Overview 1 

1.1 Scope 1 

1.2 Purpose 1 

2. References 1 

3. General . 2 

3.1. Power Supply 2 

3.2 Types of tests 3 

3.3 Standardized temperatures 4 

3.4 Use of this standard - 4 

3.5 Precautions - 5 

4. Measurements 5 

4.1 Electrical 5 

4.2 Resistance 6 

4.3 Mechanical 7 

4.4 Temperature 7 

4.5 Procedure 9 

4.6 Safety 9 

5. Machine losses and tests for losses 9 

5.1 Types of losses 10 

5.2 Stator I 2 R loss 10 

5.3 Rotor f 2 R loss 11 

5.4 Winding resistance — cold 12 

5.5 No-load test 12 

5.6 Load test... 13 

5.7 Stray-load loss 15 

5.8 Temperature test 19 

5.9 Equivalent circuit 24 

5.10 Brush-contact loss. 32 

5.11 Power factor 32 

6. Determination of efficiency 33 

6.1 General 33 

6.2 Efficiency test methods 33 

6.3 Efficiency Test Method A — Input-output 34 

6.4 Test Method B — Input-output with loss segregation 35 

6.5 Test Method Bl — Input-output with loss segregation and assumed temperature 39 

6.6 Test Method C-Duplicate machines 41 

6.7 Test Method E or El — Electrical power measurement with loss segregation 46 

6.8 Test Method F or Fl — Equivalent circuit 48 

6.9 Test Method C/F, E/F, or El/Fl — Equivalent circuit calibrated with one load point 49 

7. Other performance tests 50 

Copyright © 2004 IEEE. All rights reserved. v 



7.1. Rotor voltage 50 

7.2 Locked-rotor tests 50 

7.3 Tests for speed-torque and speed-current curves 51 

8. Miscellaneous tests , 54 

8.1 Insulation resistance 54 

8.2 High-potential test 55 

8.3 Shalt current and voltage 56 

8.4 Bearing insulation resistance.... 57 

8.5 Noise 57 

8.6 Balance and vibration . 57 

8.7 Overspeed 57 

9. Forms 58 

9.1 Test forms and support information 58 

9.2 Form A-Method A 59 

9.3 Form A2-Method A calculations 60 

9.4 Form B-Method B 61 

9.5 Form B2-Method B calculations 62 

9.6 Form Bl -Method Bl 63 

9.7 Form Bl-2-Method Bl calculations 64 

9.8 Form C-Method C 65 

9.9 Form C2-Mel.hod C Calculations 67 

9.10 Form E-Method E-El 69 

9.11 Form E2-Method E-El calculations 70 

9.12 Form F-Methods F, FL C/R E/F, and El/Fl 71 

9.1.3 Form F2-Methods F, Fl, C/F, E/F, and El/Fl calculations 72 

9.14 Test and equivalent circuit results 73 

Annex A (informative) Bibliography 74 

Annex B (informative) Typical report of test form for routine tests 75 

Annex C (informative) Typical report of test form 76 

Annex D (informative) Units of measure 77 



Copyright © 2004 IEEE. All rights reserved. 



IEEE Standard Test Procedure for 
Polyphase Induction Motors and 
Generators 



1. Overview 

1.1 Scope 

This standard covers instructions for conducting and reporting the more generally applicable and acceptable 
tests of polyphase induction motors and generators. Many of the tests described may be applied to both 
motors and generators, as needed, and no attempt is made to partition the test procedure into clauses and 
subclauses that separately apply to motors or to generators. Whenever the term motor is used, it is to be 
understood that it may be replaced by the term generator, if applicable. Likewise, whenever machine is 
used, it may be replaced by either motor or generator, if applicable. Since polyphase power systems are 
almost universally three-phase systems, the equations in this standard have been written specifically for 
three phases. When the test is performed on other than three-phase power, the equations shall be modified 
appropriately. 

1.2 Purpose 

Instructions for conducting and reporting the more generally applicable and acceptable tests are covered to 
determine the performance and characteristics of polyphase induction motors and generators. Additional 
tests, not specified herein, may be required to satisfy specific research or application needs. These proce- 
dures shall not be interpreted as requiring the performing of any specific test in a given transaction. 



2. References 

This standard shall be used in conjunction with the following standards. When the following standards are 
superseded by an approved revision, the latest revision shall apply. 

IEEE Std 43' M -2000, IEEE Recommended Practice for Testing Insulation Resistance of Rotating 
Machinery. 1 ' 2 



! IEEE publications are available from the Institute of Electrical and Electronics Engineers, Inc., 445 Hoes Lane, Piscalaway, NJ 08854, 
USA (http://standards.ieee.org/). 

-The I BEE standards or products referred to in this clause are trademarks of the Institute of Electrical and Electronics Engineers, Inc. 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

IEEE Std 1 18™ -1978 (Reaff 1992), IEEE Standard Test Code for Resistance Measurements. 



IEEE Std 1 19' M -1974, IEEE Recommended Practice for General Principles of Temperature Measurement as 
Applied to Electrical Apparatus. 

IEEE Std 120™ -1989 (Reaff 1997), IEEE Master Test Guide for Electrical Measurements in Power Circuits. 

3. General 

3.1 Power Supply 

3.1.1 Selection 

Because the performance of an induction machine is dependent not only upon the value of the line voltage 
and frequency but also on the wave shape and the balance in magnitude and phase angle of the line voltages, 
correct data can be obtained only by careful measurement with accurate instrumentation and by employing a 
suitable source of power. 

3.1.2 Waveform 

The power supply shall provide balanced voltages closely approaching a sinusoidal waveform. The har- 
monic distortion coefficient, THD, shall not exceed 0.05. The THD is defined as shown in Equation (1). 



THD = ^ ^' (1) 

where 

E ] is the root-mean-square value of the fundamental of the voltage wave, in volts (V), 
E is the total root-mean-square value of the voltage wave, in V. 

3.1.3 Voltage unbalance 

The voltage unbalance shall not exceed 0.5%. The percent voltage unbalance equals 100 times the maximum 
voltage deviation from the average voltage divided by the average voltage. 

Example: With line voltages of 220 V, 215 V, and 210 V, the average voltage is 215 V, the maximum devi- 
ation from the average is 5, and the unbalance equals (100 x 5)/215 = 2.3%. 

3.1.4 Frequency 

Eor general testing, the frequency shall be within ±0.5% of the value required for the test being conducted, 
unless otherwise specified. Any departure from the specified frequency during the test directly affects the 
efficiency obtained with Efficiency Test Methods A, B, and Bl. When these Methods are used, the fre- 
quency shall be within ±0.1% of the specified test value. 



3 IEEE Std 1 19-1974 has been withdrawn; however, copies can be obtained from Global Engineering, 15 Inverness Way East, Engle- 
woodXO 801 12-5704, USAael, (303) 792-2181 (http://global.ihs.corn/). 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

Rapid changes in frequency cannot be tolerated during testing because such variations affect not only the 
machine being tested, but also the output measuring devices. Variations in frequency during a test shall not 
exceed 0.33% of the average frequency. 

3.2 Types of tests 

3.2.1 Typical 

Polyphase induction machines are normally given a routine test, but they may also be given additional tests. 

For machine tests included in a typical routine test, refer to NEMA MG 1-2003 [B7] 4 parts 12 and 20. 

A typical form for reporting routine test data is shown in Annex B. A typical form for reporting additional 
test data is shown in Annex C. 

3.2.2 Preliminary tests 

The measurement of the winding resistance is commonly the first test performed. The resistance or the con- 
tinuity of all windings and circuits should be measured at this time. 

The ambient temperature is measured using the procedure of IEEE Std 1 19-1974. If the machine has embed- 
ded detectors, these may be used to confirm that the winding is at the ambient temperature. 

3.2.3 Idle running tests 

Running tests without load are made for the determination of core loss and windage and friction losses. 
Some other tests such as shaft voltage may also be performed under these conditions. 

3.2.4 Tests with load 

Tests with load are made for the determination of efficiency, power factor, speed, current, and temperature 
rise. Some of the miscellaneous tests outlined in Clause 8 are also made with load. For all tests with load, the 
machine shall be properly aligned and securely fastened. For readings to be used in performance determina- 
tions, the machine temperature rise shall be some value between 50% and 120% of the rated temperature 
rise. The usual procedure is to take readings at higher loads first and then follow with readings at lower 
loads. 

3.2.5 Tests with rotor locked 

It should be recognized that the testing of induction machines under locked-rotor conditions with polyphase 
power involves high mechanical stresses and high rates of heating. Therefore, it is necessary that 

a) The mechanical means of securing the machine and locking the rotor are of adequate strength to pre- 
vent possible injury to personnel or damage to equipment. 

b) The direction of rotation is established prior to the test. 

c) The machine is at approximately ambient temperature before the test is started. 

The current and torque readings shall be taken as quickly as possible, and, to obtain representative values, 
the machine temperature should not exceed rated temperature rise plus 40 °C. The readings for any point 
shall be taken within 5 seconds after voltage is applied. 



The numbers in brackets correspond to those of the bibliography in Annex A. 



Copyright © 2004 IEEE. At! rights reserved. 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

3.2.6 Choice of tests 

A complete list of tests covered by this standard is given in the table of contents. Alternate methods are 
described for making many of the tests suitable tor different sizes and types of machines and different condi- 
tions. In some cases, the preferred method is indicated. Also see 6.2. 1 . 

The schedule of factory and field tests that may be required on new equipment is normally specified by 
applicable standards or by contract specifications. The manufacturer's choice of method for factory or field 
tests on new equipment will govern in lieu of prior agreement or contract specification. 

3.3 Standardized temperatures 

3.3.1 Reference ambient temperature 

The reference ambient temperature shall be 25 °C. If the ambient temperature during any performance test 
differs from the reference ambient, the performance determinations shall be corrected to an ambient temper- 
ature of 25 °C. The actual test temperatures shall be used in the separation of losses in the no-load test and in 
determining the stray-load loss by the direct method. 

3.3.2 Specified temperature 

The efficiency of the machine, at all loads, shall be determined based on the machine being at the specified 
temperature. 

To accurately determine the values of some of the component losses with some efficiency test methods, it is 
necessary that the actual test temperatures be used in the analysis. If these test temperatures are not equal to 
the specified temperatures, appropriate corrections of the temperature dependent FR losses shall be made. 

The specified temperature shall be determined by one of the following, which are listed in order of 
preference: 

a) The specified temperature is the measured temperature rise by resistance from a rated load tempera- 
ture test plus 25 °C. Rated load is the rating identified on the nameplate at a 1 .0 service factor. 

b) The specified temperature is the measured temperature rise, as outlined in item a), on a duplicate 
machine. A duplicate machine is defined here as one of the same construction and electrical design. 

c) When the rated load temperature rise has not been measured, the specified temperature is selected 
from Table 1 based on the class of the insulation system. If the rated temperature rise is stipulated to 
be that of a lower class of insulation system than that used in the construction, the temperature value 
listed for the lower insulation class shall be used as the specified temperature. 

Preference c) shall not be used in Efficiency Test Method B; only preferences a) and b) are acceptable. 

3.4 Use of this standard 

After the test and test method are chosen, all necessary data may be obtained by following the instructions 
and precautions given in the subclause describing the test. Many of these subclauses include alternate meth- 
ods for obtaining the necessary data. Unless otherwise specified, the manufacturer may choose the method 
best suited to the facilities available. It is anticipated that the development of improved practices and new 
equipment, such as electronic and automatic devices, will result in new or improved methods of carrying out 
the intent of this test standard. New or modified methods may be used as substitutes when their results have 
been shown to be reliable and consistent with those obtained by the methods given in this test procedure. 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



Table 1 —Specified temperature for efficiency calculations when the machine rated load 

temperature is not measured 



„. pt . ,. Temperature in °C 
Class of insulation | ^^ temperature induding 

system | 25°C reference ambient) 


A 


75 


B 


95 


F 


115 


H 


130 



3.5 Precautions 



CAUTION 

Many of the tests described in these procedures subject the machine to thermal and/or mechanical stresses beyond 
normal operating limits. To minimize the risk of damage to the machine, it is recommended that all tests be per- 
formed either under the manufacturer's supervision or in accordance with the manufacturer's recommendations. 



4. Measurements 

4.1 Electrical 

4.1.1 RMS quantities 

All voltage and current measurements are root-mean-square (rms) values, unless otherwise indicated. 

4.1.2 instrument selection 

Calibrated, high -accuracy instrumentation and accessory equipment shall be used. Either analog or digital 
instruments may be used in testing. Factors affecting accuracy, particularly with nonelectronic analog instru- 
ments, are 

a) Loading of the signal source 

b) Lead calibration 

c) Range, condition, and calibration of the instrument 

Since instrument accuracy is generally expressed as a percentage of full scale, the range of the instrument 
chosen shall be as low as practical. 

Electronic instruments are generally more versatile and have much higher input impedances than nonelec- 
tronic instruments. Higher input impedance reduces the need to make corrections for the current drawn by 
the instrument. However, high input impedance instruments can be more susceptible to noise. 

Common sources of noise are 

— Inductive or electrostatic coupling of signal leads to power systems 

— Common impedance coupling or ground loops 

— Inadequate common-mode rejection 

— Conducted interference from the power line 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

Good practice requires using shielded twisted pairs for signal leads, grounding the shield at only one point, 
keeping the signal cables as far away as possible from power cables, and keeping the crossings at right 
angles when signal and power cables do cross. All exposed metal parts of instruments should be grounded 

for safety. 

The instruments shall bear record of calibration, within 12 months of the test, indicating limits of the error 
no greater than ±0.5% of full scale for general testing or no greater than ±0.2% of full scale when the test 
results are for use with Efficiency Test Method B. When several instruments are connected in the circuit 
simultaneously, additional corrections of the instrument indication may be required. 

When suitable automatic data acquisition systems or high-speed recorders are available, they may be used. 
Further information regarding the use of instruments is given in IEEE Std 120-1989. 

4.1.3 Instrument transformers 

When current and potential instrument transformers are used, corrections shall be made for ratio errors in 
voltage and current measurements, and for ratio and phase angle errors in power measurements. 

The errors of the transformers used shall not be greater than ±0.5% for general testing or not greater than 
±0.3% when the test results are for use with Efficiency Test Method B. When instrument transformers and 
instruments for measuring voltage, current, or power are calibrated as a system, the errors of the system shall 
not be greater than ±0.2% of full scale when the test results are for use with Efficiency Test Method B. 

4.1.4 Voltage 

Each of the line-to-line voltages shall be measured with the signal leads connected to the machine terminals. 
If local conditions will not permit such connections, the difference between the voltage at the machine ter- 
minals and the point of measurement shall be evaluated and the readings shall be corrected. The arithmetic 
average shall be used in calculating machine performance from the test data. 

4.1.5 Current 

The line currents to each phase of the motor shall be measured, and the arithmetic average value shall be 
used in calculating machine performance from the test data. 

4.1.6 Power 

Power input to a three-phase motor or power output from a three-phase generator may be measured by two 
single-phase wattmeters connected as in the two wattmeter method, one polyphase wattmeter, or three single 
phase wattmeters. Power readings shall be corrected for meter losses if they are significant. 

AH power measurements and calculations, both electrical and mechanical, herein are in watts. On large 
machines it may be more practical to work with power quantities expressed in kilowatts. If the unit of mea- 
sure is changed, take care that all affected values are properly converted. 

4.2 Resistance 

4.2.1 Instrument selection 

Calibrated high-accuracy instrumentation shall be used. Either analog instruments (such as a Kelvin bridge) 
or digital instruments may be used in testing. 



Copyright © 2004 IEEE. AN rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

The instruments shall bear record of calibration, within 12 months of the test, indicating limits of the error 
no greater than ±0.2% of full scale. 

When a suitable automatic data acquisition system is available, it may be used. 

4.2.2 Resistance measurement 

The procedures given in IEEE Std 1 18-1978 and IEEE Std 119-1974 should be used when measuring the 
resistance of the stator winding (and the rotor winding on wound-rotor machines). 

4.3 Mechanical 

4.3.1 Power 

Mechanical power measurements shall be taken with the greatest care and accuracy. If a mechanical brake is 
to be used, the tare, if present, shall be carefully determined and compensated for. If dynamometer output 
measurements are used, coupling and bearing friction losses must be compensated for. Properly sized dyna- 
mometers should be used, such that the coupling, friction, and windage losses of the dynamometer (see the 
note below) measured at rated speed of the machine being tested should not be greater than 15% of the rated 
output of the machine being tested; and the dynamometer should be sensitive to a change of torque of 0.25% 
of the rated torque. 

NOTE— A dynamometer is defined as a device for applying torque to the rotating member of the test machine. It is 
equipped with means for indicating torque and speed, and is not limited to a cradle base construction. An in-line torque 
transducer may be used to provide a direct measurement of torque at the test machine shaft 5 

The eirors of the instrumentation used to measure mechanical torque shall not be greater than ±0.2% of full 
scale. 

4.3.2 Speed and slip 

4.3.2.1 Instruments 

Stroboscopies or digital tachometer methods shall be used to determine slip or speed. When a stroboscope is 
used to measure slip, the power supply for the stroboscope shall have the same frequency as the motor 
power supply. 

When the speed is measured, the instrumentation used shall have an error of not greater than ±1 .0 r/min of 
the reading. 

4.4 Temperature 

4.4.1 Methods of measuring temperatures 

The temperature of various machine parts or coolant may be measured by the following: 

a) Alcohol thermometer 

b) Local temperature detector 

c) Embedded detector 

d) Winding resistance 



Notes in text, tables, and figures are given for information only, and do not contain requirements needed to implement the standard. 



Copyright © 2004 IEEE. Ait rights reserved. 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

The temperatures measured by any of these methods can deviate substantially from those determined by the 
other listed methods. Therefore, the temperatures so measured by one method shall not be interpreted in 
relation to standards written in terms of the other methods. 

For general information, refer to IEEE Std 1 19-1974 and IEEE Std 1™-1986 [B5]. 

4.4.1.1 Alcohol thermometer 

Alcohol thermometers are used to measure the temperature of accessible parts of the machine under test. 

Temperatures taken by the alcohol thermometer method may be measured on the following parts: 

a) Stator coils, in at least two places 

b) Stator core, in at least two places 

c) Ambient 

d) Air discharged from frame or air discharge ducts, or internal coolant discharged to the inlet of cool- 
ers of machines with recirculating cooling system 

e) Frame 

f) Bearings (when part of the machine) 

The alcohol thermometers should be located to obtain the highest temperature for the item being measured, 
except for ingoing and discharge air or other coolant temperature, for which they should be placed to obtain 
average values. 

4.4.1.2 Local temperature detector 

The local temperature of various parts of a machine can be determined using local temperature detectors 
such as 

a) Thermocouples 

b) Small resistance thermometers 

c) Thermistors 

The maximum dimension of the detecting element of these local temperature detectors should not exceed 
5 cm. 

These detectors can be used to measure temperatures in the same locations as alcohol thermometers, see 
4.4. 1 .1 , and are commonly used in areas on or within the machine that are not accessible to an alcohol ther- 
mometer. They are frequently installed as permanent parts of a machine and are available for use during 
tests. 

The detecting element should be located on or in close thermal proximity to the part at which the local 
temperature is to be measured to obtain the highest temperature for that item, except for the incoming and 
discharge air or other coolant temperature, for which it should be placed to obtain the average value. 

Specially designed instruments should be used with local temperature detectors to prevent the introduction 
of significant errors or possibly damaging the detector during the measurement. Because of the variety of 
materials used in these detectors, take care to insure the instrument selected is suitable for the specific mate- 
rial used in the detector or is matched to the resistance value when resistance thermometers are used. Many 
ordinary resistance measuring devices may not be suitable for use with resistance thermometers because of 
the relatively large current that may be passed through the resistance element while making the 
measurement. 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

4.4.1.3 Embedded detector 

Embedded detectors, such as resistance temperature detectors (rtds) or thermocouples, are commonly used 
on large machines to monitor the winding temperature during operation and are available for use during 
machine testing. They are usually installed between coil sides within a stator slot. An rtd gives a reading that 
is the average of the temperature of the two abutting coil sides over the length of the sensing element. A 
thermocouple measures the temperature of the spot where the thermocouple junction is located between the 
two coil sides. 

The precautions on the selection of instrumentation in 4.4.1 2 also apply here. 

4.4.1.4 Winding resistance 

The average temperature of a winding can be determined by comparing the resistance of the winding at the 
temperature to be determined with the resistance at a known temperature. This method utilizes the character- 
istic of the conductor material where, in the temperature range of interest, the winding resistance changes in 
direct proportion to the winding temperature. See 5,2.1 . 

4.4.2 Ambient temperature 

The procedure of IEEE Std 1 19-1974 should be followed in measuring the ambient temperature. 

4.5 Procedure 

Whenever a series of increasing or decreasing readings of data are made, care should be taken in each case 
not to overrun the desired setting to avoid the introduction of hysteresis losses caused by a reversal in the 
direction of the test. 

4.6 Safety 



CAUTION 

Because of the dangerous currents, voltages, and forces encountered, safety precautions shall be taken for all tests. 
No attempt is made here to list or review the manifold general safety precautions that are well established through- 
out industry. However, this standard includes special safety precautions applicable to the particular tests described. 
All tests should be performed by knowledgeable and experienced personnel. 



5. Machine losses and tests for losses 

This clause identifies the losses of an induction machine and describes tests and calculations to be used to 
determine these losses and the machine performance characteristics. The results of these tests are used in 
making the efficiency and performance determinations of Clause 6. All tests and procedures of this clause 
are not required in all of the efficiency analysis methods. Refer to the specific efficiency test method of 
interest in Clause 6. 



Alternate test methods are presented where appropriate. 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 11 2-2004 | EEE STANDARD TEST PROCEDURE FOR 

5.1 Types of losses 

The losses of aa induction machine include: 

— Stator l 2 R loss, see 5.2 

— Rotor I 2 R loss, see 5 .3 

— Friction and windage loss, see 5.5.4 

— Core loss , see 5 .5 .5 

— Stray-load loss, see 5.7 

— Brush-contact loss, see 5.10 

Other individual tests or procedures are required to support some of the efficiency test methods. These 
include: 

— Shaft power, see 5 .6 . 1 . 1 

— Dynamometer correction, see 5.6.1 .2 

— Equivalent circuit, see 5.9 

— Temperature test, see 5,8 

5.2 Stator l 2 R loss 

For a three-phase machine, the stator I 2 R loss, P SIR , in watts is as shown in Equation (2). 

P s/R = L5I 2 R = 3T 2 *, (2) 

where 
/ is the measured or calculated current per line terminal, in amperes (A), 

R is the dc resistance, in ohms, between any two line terminals™ corrected to the appropriate 

temperature, if required (see 5.2.1), 
R\ is the per phase dc resistance, in ohms (see 5.9). 

5.2.1 Resistance correction for temperature 

Some of the test analyses require that the winding resistance be adjusted or corrected to another temperature. 
With the winding resistance value, R a , available at a known temperature, t a , the resistance value at any other 
temperature, t b , can be determined using Equation (3). 

R h _ (3) 



'« + *1 



where 



R a is the known value of winding resistance, in ohms, at temperature t a> 
t a is the temperature, in °C, of winding when the resistance R a was measured, 
t b is the temperature, in °C, to which the resistance is to be corrected, 
R b is the winding resistance, in ohms, corrected to the temperature t b , 
A-j is 234.5 for 100% IACS conductivity copper, or 225 for aluminum, based on a volume 
conductivity of 62%. 

For other winding materials, a suitable value of k x (inferred temperature for zero resistance) shall be used. 
1 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

When a winding resistance value is calculated for a different temperature, t a and t b shall be based on the 
same method of measure. See 4.4. When any winding 1 2 R loss is determined at a temperature, the calcula- 
tion shall use a winding resistance value that is based on the winding being at an average (or uniform) 
temperature. The specified temperature, the temperature at shutdown (measured by resistance) and the tem- 
perature when the cold resistance is obtained are all average temperatures. It may not be possible to obtain 
average temperature readings during some tests (such as during a load test) and special procedures for eval- 
uating the average winding temperature using local detector readings may be necessary. One such procedure 
is utilized in 6.4.2.4. 

5.3 Rotor i 2 R loss 

The rotor I 2 R loss, including brush-contact losses for wound-rotor machines, shall be determined from the 
slip using Equation (4) or Equation (5) as follows: 

motor rotor / R loss = (measured stator input power - stator I"R loss - core loss) x s (4) 

2 2 

generator / R loss = (measured stator output power + stator / R loss + core loss) x s (5) 

where 

s is slip, in per unit (p.u), with synchronous speed as base speed, see Equation (8). 

All power items are in watts (W). 

5.3.1 Slip 

The slip speed, in r/min, can be measured directly by stroboscopic means or it can be calculated from the 
measured speed. This value then must be converted to a numeric or per unit value for use in the analyses. 

The slip speed is the difference between synchronous speed and measured speed, in r/min [see 
Equation (6)]. 

slip speed - n s + n t (6) 

where 

n v - 120 x-^ (7) 

P 

and 

n s is the synchronous speed, in r/min, 

n t is the measured speed, in r/min, 

/ is the line frequency, in hertz, 

p is the number of poles. 

Slip expressed as a per unit quantity is 



slip speed (in r/min) 
synchronous speed (in r/min) 



(8) 



NOTE— It is assumed the number of poles is known. If not, the number of poles can be determined by using no-load test 
data and by rearranging Equation (7) to solve for p. (Multiply the input frequency times 120 and then divide by the mea- 
sured idle speed.) This calculation will result in a value very near an even number (0% to 4% high). Round this value to 
the nearest lower even number (such as, 2,4, 6, etc.) and this is the number of poles in the machine. 



Copyright © 2004 IEEE. Alt rights reserved. 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

5.3.2 Slip correction for temperature 

The slip, in p.u., is directly related to the rotor resistance. Thus, the slip can be corrected for temperature 
using the same basic relationship as for resistance and temperature. The corrected value of slip is used in 
determining the rotor l 2 R loss in the final adjustments when using Efficiency Test Methods B, Bl, and C. 
Use Equation (9) to correct the test slip measurements to the specified stator temperature. 

where 

s s is the slip, in p.u., corrected to specified stator temperature, t u 

s t is the slip, in p.u., measured at stator winding temperature, t h 

t s is the specified temperature for resistance correction, in °C, see 3.3.2, 

t t is the observed stator winding temperature during load test, in °C, 

k\ is 234.5 for 100% IACS conductivity copper, or 225 for aluminum, based on a volume 
conductivity of 62% (based on rotor conductor material). 
NOTES: 

J —For other rotor winding materials, a suitable value oi k\ (inferred temperature for zero resistance) shall be used. 
2— The values for t s and t t shall be based on the same method of measurement of temperature, see 5.2.1 . 

5.4 Winding resistance— cold 

With the machine at ambient temperature, measure the terminal -to- terminal winding resistance with the 
machine connected in the configuration to be used in the efficiency testing. Measure and record all combina- 
tions, i.e., T1-T2, T2-T3, and T3-T1 , to assure that the specific precise value needed in further analyses will 
be available. Also measure and record the ambient temperature. See 3.2.2. 

5.5 No-load test 

This test is performed by running the machine as a motor at rated voltage and frequency with no connected 
load. When separation of no-load losses is to be accomplished, run this test and read temperature, voltage, 
current, and power input at rated frequency and at voltages ranging from 1.25% of rated voltage down to the 
point where further voltage reduction increases the current. 

5.5.1 Bearing loss stabilization 

Some motors may experience a change in friction loss until the bearings reach a stabilized operating condi- 
tion. In grease lubricated antifriction bearings, stabilization will not occur until there is no excess grease 
present in the path of the moving parts. This may require a number of hours of running to completely stabi- 
lize the no-load input power. Stabilization can be considered to have occurred whenever the power input at 
no-load does not vary by more than 3% between two successive readings at the same voltage at half-hour 
intervals. This bearing loss stabilization test may not be necessary if a temperature test has been performed 
prior to no-load testing. 

5.5.2 No-load current 

The average of the line currents at rated voltage is the no-load current. 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

5.5.3 No-load losses 

The measured input: power is the total of the losses in the motor at no-loaci. These losses consist of the stator 
I 2 R, friction (including brush-friction loss on wound-rotor motors), windage, and core losses. 

5.5.4 Friction and windage 

The friction and windage loss may also be determined by performing a linear regression analysis using three 
or more lower points of the power versus voltage squared curve. To determine the friction and windage loss, 
subtract the stator I 2 R loss (at the temperature of the test) from the total losses (i.e., input power) at each of 
the test voltage points and plot the resulting power curve versus voltage, extending the curve to zero voltage. 
The intercept with the zero voltage axis is the friction and windage loss. This intercept may be determined 
more accurately if the input power minus stator I 2 R loss is plotted against the voltage squared for values in 
the lower voltage range. 

5.5.5 Core loss 

The core loss, P/ z , at each test voltage is obtained by subtracting the value of friction and windage loss 
(determined in 5.5.4) from the input power minus stator fiR loss (determined in 5.5.4). A plot of core loss 
versus voltage can be constructed for use in determining the core loss at any desired voltage. 

5.6 Load test 

Most of the efficiency test methods require that a load test be performed either to directly determine the effi- 
ciency as in Efficiency Test Method A or to determine the stray-load loss as in Efficiency Test Methods B, 
Bl, and C. The machine is coupled to a load machine and is subjected to loads at four load points approxi- 
mately equally spaced between not less than 25% and up to and including 100% load, and two load points 
suitably chosen above 100% load but not exceeding 150% load. A spread in load test points is necessary to 
determine the efficiency accurately over the entire load range of the machine and more than six load points 
may be used if desired. 

Readings of electrical power, current, voltage, frequency, speed or slip, torque, stator winding temperature 
or stator winding resistance, and ambient temperature shall be obtained at each load point. In loading the 
machine, start at the highest load value and move in descending order to the lowest. 

The common loading means are as follows: 

— Dynamometer. See 5 .6.1 . 

— Direct loading without torque measurement. See 5.6.2. 

— Duplicate machine loading. See 5.6.3. 

5.6.1 Dynamometer loading 

For this test, the machine is loaded by means of a mechanical brake or dynamometer (see 4.3.1) and tested as 
described in 5.6. 

This test should be performed as quickly as possible to minimize temperature changes in the machine during 
testing. 

For Efficiency Test Method B, the temperature of the stator winding shall be within 10 °C of the hottest 
temperature reading recorded during the rated load temperature test on this or the duplicate machine prior to 
the start of recording data for this test. 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



5.6.1.1 Mechanical power 

The shaft power, in W, of the machine under test at each load point is obtained from Equation (10) using the 
test values of torque and speed. The torque may require correction for dynamometer losses. See 5.6.1 .2. 



P = 



2xn s T 
60 



/Co 



(10) 



where 

P 

n t 
k 2 
T 



is shaft power, in watts (W), 

is the measured speed or the speed calculated using measured slip, in r/min, 

is 9.549 for torque in Newton meters (N*m), 

is the torque , in N-m. See Equation (1 1) if dynamometer correction is required. 



T = T t ±T D 



(ID 



where 

T t is a measured machine shaft torque, in N*m, 

Tp is the dynamometer correction from Equation (1 2), in N-m. 

NOTE— In Equation (11), use the plus sign for motoring and the minus sign for generating. The terms motoring and 
generating refer to the action of the machine under test. 

5.6.1.2 Dynamometer correction 

A dynamometer no-load test combined with a machine no-load test can be used to determine the dynamom- 
eter correction to compensate for coupling and bearing friction losses of the dynamometer. This test is not 
generally necessary when the load on the test machine is measured using a torque transducer in line with the 
shaft of the machine because the low coupling losses do not significantly affect efficiency. The machine is 
operated as a motor at rated voltage while coupled to the dynamometer and all electrical power removed 
from the dynamometer. The electrical input power, voltage, current, slip or speed, torque, and stator winding 
resistance or stator winding temperature shall be recorded. The machine is then uncoupled from the dyna- 
mometer and operated at no load at rated voltage with the electrical input power, voltage, current, slip or 
speed, and stator winding resistance or stator winding temperature again recorded. Test data from a no-load 
test point at rated voltage (see 5.5) may be used for the no-load data when it is not practical to uncouple the 
machine from the dynamometer for this test. The dynamometer correction, in N*m, is determined from 
Equation (12). 



k-> x 



Pa-Pb 



(12) 



where 



P A ~ (Pin A ~ PsiRA ~~ P h) x ~ s .4) 
P B ~ \P'inB ~ Ps/RB ™ P h* 

and 



(13) 
(14) 



°For other units of measure, see Annex D. 



14 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

To is the correction to be applied the load torque before performing the power calculation of 5.6.1 .1 , 
P inA is input power, in W, when the machine under test is operated as a motor when coupled to a 

dynamometer with the dynamometer armature circuit open, (Test A), 
Psira is the stator PR loss, in W, during Test A, 
sa is slip, in p.u., during Test A, 

Ta is the torque, in N-m, registered by the dynamometer during Test A, 
iia is the measured speed or the speed calculated using measured slip, in r/min, during Test A, 
PinB is the input power, in W, during a no load test at rated voltage, (Test B), 
PsiRB is the stator PR loss, in W, during a no load test at rated voltage, (Test B), 
P h is the core loss, in W, during a no load test at rated voltage, 
ko is 9.549 for torque in N-m. 

5.6.2 Direct loading with no torque measurement 

To obtain the required data in Efficiency Test Method E, it is necessary to couple, belt, or gear the machine 
to a variable load and then perform the test as described in 5.6. A reading of torque at each load point is not 
required. 

The stator winding resistance for each load point can be estimated by comparing the temperature rise 
measured by an embedded temperature detector, a temperature sensor located on the stator coil end, or the 
air outlet temperature rise, with corresponding temperature rise measurements obtained as steady-state 
values during a temperature test. When no temperature test is performed on this or on a duplicate machine, 
the calculations in the efficiency analysis are made with the stator winding resistance corrected to the total 
specified winding temperature assumed for the test. See 3.3.2, item c). 

5.6.3 Duplicate machine loading 

The load test for Efficiency Test Method C utilizes two duplicate machines coupled together. Varying the 
frequency of the voltage applied to one machine controls the load level and the direction of power flow 
between machines. This procedure is presented in 6.6. 

5.7 Stray-load loss 

The stray-load loss is that portion of the total loss in a machine not accounted for by the sum of the friction 
and windage loss, the stator PR loss, the rotor PR loss, and the core loss. 

5.7.1 Indirect measurement 

The stray-load loss is determined indirectly by measuring the total losses, and subtracting from these losses 
the sum of the friction and windage, core loss, stator PR loss, and rotor PR loss. The remaining value is the 
stray-load loss. The indirect measurement procedure is used in Efficiency Test Methods B, Bl , C, and C/F 
(see 6.4, 6.5, 6.6, and 6.9). 

5.7.2 Direct measurement 

Direct measurement of the stray-load loss is used in efficiency methods E, F, and E/F (see 6.7, 6.8, and 6.9). 
The fundamental frequency and the high-frequency components of the stray-load loss are determined and 
the sum of these two components is the total stray-load loss. 



Copyright © 2004 IEEE. Al! rights reserved. 1 5 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

5.7.2.1 Stray-load loss at fundamental frequency 

The stray-load loss occurring at fundamental frequency is determined by applying balanced polyphase 
voltage to the stator-winding terminals with the rotor removed. The electrical input minus the stator I 2 R loss 
at test temperature is equal to the fundamental frequency stray -load loss. During this test, bearing brackets 
and other structural parts in which current might be induced shall be in place. The currents used in making 
this test and that described in 5.7.2.2 are identified as /,, with values established by Equation (15) for 
magnitudes covering the range of loads from 0.25 to 1 .5 times rated load, as indicated by the appropriate test 
procedure. Vary the applied voltage to obtain the established currents and record input power and current 
and the winding temperature. 



1, = J{P^lf) (15) 

where 

It is the value of stator winding current, in A, during stray-load loss test, 

Iq is the value of no-load current, in A (see 5 .5 .2.), 

/ is the operating value of stator line current, in A, for which stray-load loss is to be determined. 

5.7.2.2 Stray-load loss at high frequency 

The stray -load loss occurring at high frequencies is determined by a reverse rotation test. With the motor 
completely assembled, apply balanced polyphase voltages at rated frequency at the stator winding terminals. 
The rotor is then driven by external means at or near synchronous speed in the direction opposite to the sta- 
tor field rotation and the electrical input to the stator winding is measured. 



CAUTION 

To prevent overheating during this test of machines with unidirectional cooling systems, it is recommended that 
such machines be driven by an external means at or near synchronous speed in the normal direction for proper ven- 
tilation and that the power connections to the stator he reversed to have the stator field rotation opposite to that of 
the mechanical rotation. Record the electrical input to the stator during the test. 



The mechanical power required to drive the rotor is measured both with and without current in the stator 
winding. A balanced polyphase voltage is applied to the stator winding to obtain the same values of current 
magnitude as used in 5.7.2.1 . The magnitude of the currents must be the same. For wound-rotor motors, the 
rotor terminals shall be short-circuited. At each current point, measure and record the mechanical power to 
drive the motor, the electrical input power and c urrent, and the winding temperature. Record mechanical 
power input at zero input current. 

NOTE-The low power factors encountered during the tests specified in 5.7.2.1 and 5.7.2.2 make it imperative that phase 
angle error corrections be applied to all wattmeter readings. Refer to IEEE Std 120-1989. 

5.7.2.3 Stray-load loss calculation 

The st ray -load loss is determined by combining the above fundamental frequency and the high-frequency 
components. The stray-load loss, P$ L , in W, is shown in Equation (16). 

P S l = Psu + P SI , (16) 

where 
f*SLs = (A ~ stator P-R loss), in W, and is the fundamental frequency stray-load loss, 

1 6 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

P SLr = (P r - P m ) - (P rr - P SLs ~ stator I 2 R loss), in W, and is the high-frequency loss, 

P m is the mechanical power, in W, required to drive rotor without voltage being applied at stator 

winding terminals, 
P r is the mechanical power, in W, required to drive rotor with voltage applied at stator winding 

terminals, 
P rr is the electrical input, in W, to stator winding during reverse-rotation test, 
P s is the electrical input, in W, to stator winding with rotor removed. 

Stator I 2 R loss shall be calculated as in Equation (2) using the current and resistance at each point. 

5.7.2.4 Smoothing the test data 

Smooth the raw data; (P r - P m ) 9 P s and P rr \ from the tests of 5.7.2.1 and 5.7.2.2 using a series of three 
regression analyses. Each regression analysis is of the log of a test power vs. the log of the test current. The 
result of these analyses is shown in Equation (17) through Equation (39). 

(17) 

(18) 

(19) 



A is the y intercept on a log-log plot (a constant), 

TV is the slope on a log-log plot (approximately 2), 

l t is the observed line current during the stray -loss test, in amperes. 

If the data are accurate, each curve will conform to a square-law relationship between power and current. 
Thus, the correlation factor from the regression and exponent for each curve both serve as indicators of data 
accuracy. 

5.7.2.5 Calculating stray-load loss at a specified point 

Determine an approximate value of rotor 2current /S corresponding to the rated value of stator line current, 
/, as in Equation (20). 



Pr~ 


■p m = M*/ 


P s : 


= mi,) 


Prr 


= M'/ 


where 





^Jp-il (20) 

where 

/ is the rated value of stator line current, in A, 

/o is the value of no-load stator current, in A. 

Using the value of rotor current 1\, calculate a value of stray -load loss P'sl for three-phase machines as 
follows in Equation (21); 

p*sl= A } (r 2 f ] + 2A 2 (r 2 f 2 ~A 3 (r 2 f 3 ~3x {r 2 f x (2/?,,-/e lr ) (21) 

Copyright © 2004 IEEE. All rights reserved. 1 7 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

where 

P'sl is the value of stray-load loss, in W, for approximate value of rotor current corresponding to rated 

load, 
7*2 is the approximate value of rotor current, in amperes, corresponding to rated load from 

Equation (20), 
R\ s is the stator resistance per phase, in ohms, during the rotor removed test at test temperature 

(see 5.7.2.1), 
R\ r is the stator resistance per phase, in ohms, during the reverse rotation test at test temperature 

(see 5.7.2.2). 
NOTE— The resistance values above are per phase values that are equal to one half of the line-to-line values. 

The value of stray-load loss, Psl> for any load point is calculated as shown in Equation (22). 

P SL =^f (22) 

The value of rotor current for each load point to be considered in the efficiency analysis is determined by 
Equation (23). 



>i = V^o 2 (23) 

where 

/ is the value of stator line current, in A, for which stray-load loss is to be determined, 

}{) is the value of no-load current, in A. 

5.7.3 Alternate direct method for wound-rotor motors 

This method is used with Efficiency Test Methods E, F, and E/F (see 6.7, 6.8, and 6.9). In this method, the 
rotor is excited with direct current, and the stator winding terminals are short-circuited with ammeters 
included to read the stator current. The rotor is driven by external means at or near synchronous speed. The 
rotor excitation is adjusted until the current circulating in the stator winding has the value for which a stray- 
load loss determination is desired. The mechanical power required to drive the rotor with excitation, P r ^ and 
without excitation, P m , is measured and the stray-load loss, P$l, is calculated as shown in Equation (24). 

P sl - p r - p m _ statorwinding/ 2 /? loss (24) 

If six load points are used, the accuracy can be improved by plotting stray-load loss vs, stator winding 
current squared and by following a smoothing procedure similar to that used in 5.7.2.4. The stator I 2 R in 
Equation (24) is at the temperature during the test. 

5.7.4 Assumed stray-load loss 

An assumed value of stray-load loss is used with Efficiency Test Methods El, Fl, and El/Fl (see 6.7, 6,8, and 
6.9). If the stray-load loss is not measured and it is acceptable by applicable standards or by contract 
specifications, the value of stray-load loss at rated load may be assumed to be the value as shown in Table 2, 

For other than rated load, it shall be assumed that the stray-load loss, Psl, is proportional to the square of the 
rotor current and a value can be calculated using Equation (22) with P^l equal to the assumed value from 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 

Table 2— Assumed values for stray-load loss 



IEEE 
Std 112-2004 



Machine rating kW 


Stray-load loss percent 
of rated load 


1-90 


1 .8% 


91-375 


1 .5% 


376-1850 


1 .2% 


1851 
and greater 


0.9% 



Table 2, P 2 equal to the rotor current corresponding to rated load, and h being the rotor current at the load 
where the stray-power loss is to be determined. 

5.8 Temperature test 

5.8.1 Purpose 

Temperature tests are made to determine the temperature rise of certain parts of the machine above the 
ambient temperature when running under a specified loading condition. Subclauses 5,8.2 through 5.8.5 are 
guides for the test and for the treatment of the data. 

5.8.2 General instructions 

The machine shall be shielded from air currents coming from pulleys, belts, and other machines. A very 
slight current of air may cause great discrepancies in the temperature test results. Conditions that result in 
rapid change of ambient air temperature shall not be considered satisfactory for temperature tests. Sufficient 
floor space shall be provided between machines to allow free circulation of air. 

5.8.2.1 Measuring devices 

Temperature measuring devices shall be in accordance with IEEE Std 119-1974. At the start of the 
temperature test, all instruments shall be checked to make certain that there are no appreciable instrument 
errors due to stray field effects. 

5.8.2.2 Temperature of rotors and other parts of totally enclosed machines 

The temperature of rotors and other parts of totally enclosed machines, for which the thermometer method is 
used, shall be obtained after shutdown by applying the thermometer to the hottest parts that can be made 
quickly accessible by removing covers. 

5.8.3 Loading method 

The loading method for making the temperature test shall be one of the following: 

a) Actual loading method 

b) Primary-superposed equivalent method 

c) Forward stall equivalent method 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



5.8.3.1 Actual loading method 

The actual loading method is one in which the machine is loaded as a motor or generator under the rated (or 
desired) condition. 

5.8.3.2 Primary-superposed equivalent loading method 

Primary-superposed equivalent loading method is one in which the machine is operated at no-load from a 
main power source and with a low-voltage auxiliary power of different frequency superposed. A typical 
configuration is shown in Figure 1. The phase rotation of the auxiliary power shall be chosen to have the 
same direction as that of the main power. 

Generally, temperature rises are determined by running with the superposed power supplied at a frequency 
10 Hz below rated frequency, and with the voltage so adjusted that the current to the machine is equal to the 
rated value. 



Rated 

Frequency 

Primary Power 

Source 






— moc?- 



Series 
Transformer 



To 

Machine 

Under Test 



Lower Frequency 
Auxiliary Power Source 



Metering 
Location 



Figure 1— Typical connection for superposed equivalent loading 



NOTES 



1-When the loading for the temperature test is the superposed equivalent loading method, the slip loss does not apply, 
and a tested value of rotor P-R loss, per 5.3, cannot be obtained. Therefore, when equivalent loading is used, calculated 
rotor Aft s h a ]j be used in determining efficiency by the segregated loss method. See 6.6. 

2-Inasmuch as there are oscillatory torques applied to the stator and rotor of the machine supplied with power at two dif- 
ferent frequencies, vibration will be abnormal during this condition, and normal criteria for vibration do not apply. 
Vibration should be monitored and compared against acceptable limits for the machine being tested. After the machine 
has been heated, the auxiliary frequency can be removed and vibration can be measured with rated frequency and volt- 
age applied to determine the vibration of the machine operating at normal running temperature. The machine will cool 
rapidly after removing the auxiliary frequency. Therefore, temperature should be monitored by thermocouple to ensure 
that vibration is measured while the motor is within 25% of normal operating temperature. 

5.8.3.3 Forward stall equivalent loading method 

The forward stall (also known as forward short circuit) loading method is one in which the machine to be 
tested is driven at rated speed in its normal direction of rotation by an auxiliary drive motor while the 
terminals of the motor under test are connected to a reduced voltage fixed frequency supply with phase 
sequence selected to give rotation in the normal direction. Generally, the supply frequency is 20% to 25% 
less than the machine rated (nameplate) frequency. The auxiliary drive motor should have a power rating of 
at least 10% that of the motor under test. 

With the auxiliary drive motor driving the coupled system at rated speed, the voltage at the machine 
terminals is adjusted until the line current equals the rated current. The machine under test is then operating 
as an induction generator with a slip of approximately -25% (-0.25 p.u.). 



20 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

With the reduced voltage on the machine, the stator iron losses are lower than under actual loading 
conditions of 5.8.3.1. To compensate for this difference, the test is supplemented by two no-load 
temperature tests at rated frequency, one at rated supply voltage and one at the stator voltage used during the 
forward stall test. The difference between the stator temperature rises in these two tests is added to 
temperature rise measured during the forward stall test and the resultant rise is to be considered as the total 
temperature rise. 

NOTE— During the load application phase, as the supply voltage is raised from zero, the current should first reduce and 
then reverse. If the current increases without this initial reversal, the phase sequence of the machine relative to the sup- 
ply is incorrect. If this occurs, stop the test, change the phase sequence, and restart the test. 

5.8.4 Procedure 

The machine may be loaded by one of the methods outlined in 5.8.3. The loading may be determined by 
direct measurement of output or input. 

A machine having multiple ratings (such as a multispeed or oil-well service machine) shall be tested at the 
rating that produces the greatest temperature rise. Where this cannot be predetermined, the machine shall be 
tested at each rating. 

A dual-frequency machine may be tested at whichever frequency is available. If both frequencies are 
available, it should be tested at the frequency that results in the maximum temperature rise. 

Unless otherwise stipulated by the efficiency test method, a machine having a service factor greater than 1 .0 
shall be tested at the service factor load to establish that the machine meets insulation class temperature 
limits, except when temperature rise at a specified loading forms part of the machine rating. However, the 
temperature rise at 1 .0 service factor shall be used in calculating machine performance in accordance with 

3.3.2. 

When the temperature test is at the service factor load rather than rated load (1.0 service factor), the 
temperature rise by resistance of the motor at rated load can be derived by varying the temperature rise by 
the square of the current. For the efficiency calculations, the total temperature (specified temperature) will 
be the rise at rated load plus 25 °C. 

When the analysis shows that the temperature test was performed near but not at the rated load, 
Equation (25) also may be used to adjust the test temperature rise to a rated load temperature rise. If the test 
load is below rated load, this adjustment must be made. 



Te mp er a ture Rise med — Te mp erature R ise iesx x 



5.8.4.1 Initial conditions 



rated 
• 'test - 



(25) 



Temperature tests on continuously rated machines can be started with the machine at any temperature less 
than rated temperature. Unless otherwise specified, a test on a short-time rated machine shall commence 
only when machine parts are within 5 C C of the ambient temperature. 

5.8.4.2 Permissible overloading 

On continuously-rated machines, when a long time is required to attain steady temperature, reasonable (25% 
to 50%) overloads during the preliminary heating period are permissible in order to shorten the time of test. 
Any overload shall be removed before the temperature goes above the expected final temperature. 



Copyright © 2004 IEEE. All rights reserved. 21 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

5.8.4.3 Temperature measurement 

The machine should he equipped with devices to measure the temperature of the windings, the stator core, 
the incoming cold coolant, and the exhaust hot coolant. Each method of measurement, see 4.4, is best suited 
for particular parts of machine. Thus, in a given test, it may be desirable to use all four methods to measure 
the temperature in the various parts of the machine. 

Temperatures taken by the alcohol thermometer method (see 4.4.1.1) may be measured during the 
temperature tests and, if specified, after shutdown. 

Local temperature detectors (see 4.4.1.2) may be used to measure the temperature of various parts of the 
machine during the temperature test. When several local temperature detectors are used to measure the 
winding temperature, the temperature measurements of all should be recorded, with the maximum of these 
values reported as the temperature of the winding by local detector. Readings after shutdown are not 
normally required 

Temperatures of the windings of machines equipped with embedded detectors should be determined by the 
embedded-detector method (see 4.4.13) during the temperature test. Temperature measurements of all 
embedded detectors shall be recorded, and the maximum of these values shall be reported as the temperature 
of the winding by embedded detector. Readings after shutdown are not normally required. 

The temperature of the stator (and rotor of wound -rotor machines) winding shall be determined by the 
winding resistance method (see 4.4.1.4) after shutdown (see 5.8.4.4 and 5.8.4.5). The resistance may be 
measured between any two line terminals for which a reference value of resistance has been measured at a 
known temperature. If equipment is available to measure the winding resistance during the temperature test, 
this may be used if the results have the necessary accuracy. 

Other temperature sensing devices on the machine such as bearing and/or lubricant temperature detectors 
should also be noted and recorded. 

5.8.4.4 Termination of test 

The test shall be continued for the specified time (for machines not continuously rated), or until constant 
temperature rises have been reached. For continuously rated machines, readings of machine input, machine 
output (as applicable), and all temperatures (including ambient temperature) shall be taken at intervals of 30 
minutes or less. For noncontinuously rated machines, readings shall be taken at intervals consistent with the 
time rating. For continuous rated machines, the temperature test shall continue until there is 1 °C or less 
change in temperature rise above the ambient temperature over a 30 -minute period. 

If the winding resistance is measured during the temperature test, see 5.8.4.3; take a reading at the time of 
shutdown, provided the results have the necessary accuracy. Measurements after shutdown are not required. 

5.8.4.5 Resistance at shutdown 

The winding resistance shall be measured after shutdown and this shall be used to determine the final 
temperature of the machine and its temperature rise. This measurement requires a quick shutdown of the 
machine at the end of the temperature test and quick application of the leads from the resistance measuring 
device. A carefully planned procedure and an adequate number of people are required to obtain readings 
soon enough to give reliable data. 

If the initial resistance reading is obtained within the time interval indicated in Table 3, this reading is 
accepted as the resistance measurement. If the initial resistance reading cannot be made within the time 
delay given by the table, it shall be made as soon as possible, and additional resistance readings shall be 
taken at intervals of 30-60 seconds for a minimum of 10 readings. 



22 Copyright © 2004 IEEE. AN rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



Table 3— Maximum time delay in resistance measurements 



Machine rating 


Time delay after 
switching off power 

(seconds) 


KVA 


k\\ 


50 or less 


38 or less 


30 


Above 50 to 200 


Above 38 to 150 


90 


Above 200 


Above 150 


120 



A curve of these readings shall be plotted as a function of time, and shall be extrapolated to the time delay 
given by Table 3 for the rating of the machine. A semi -logarithmic plot is recommended, in which resistance 
is plotted on the logarithmic scale. The value of resistance thus obtained shall be considered as the resistance 
at shutdown. If successive measurements show increasing resistance after shutdown, the highest value shall 
be taken. Where the first reading cannot be taken within twice the time delay given by Table 3, the time 
shall be subject to agreement. 

5.8.4.6 Care in measurement 

Extreme care shall be taken to secure accurate resistance measurements because a small error in measuring 
resistance will cause a comparatively large error in determining the temperature. 

5.8.5 Temperature rise 

When the machine is ventilated by the immediately surrounding air, the temperature rise is the observed 
machine temperature minus the ambient temperature. When the machine is ventilated by air obtained from a 
remote source or a heat exchanger, the temperature rise is the observed machine temperature minus the 
temperature of the air entering the machine or exiting the heat exchanger when part of the machine. 

Machines may be tested at any altitude not exceeding 1000 m and with cooling air temperatures between 
I0°C and 40°C without correction of temperature rise. 

NOTE— At higher altitudes, the temperature rise will be greater than at sea level. While an exact conversion is not avail- 
able, a commonly used method allows for the influence of altitude. For each 100 m above 1000 m, the temperature rise 
is reduced by J % to obtain the rise expected at sea level . 

5.8.5.1 Calculation of temperature 

The temperature of the winding, using the winding resistance, is calculated using Equation (26). 



x (^ + /c i) -* 



(26) 



where 
tt 
Rr 

Rb 



is the total temperature of winding, in °C, when R } was measured, 

is the resistance measured during test, in ohms, 

is the reference value of resistance, in ohms, previously measured at known temperature t^ t 

is the temperature, in °C, of winding when reference value of resistance /?£ was measured, 

is 234.5 for 100% International Annealed Copper Standard (I ACS) conductivity copper, 

or 225 for aluminum, based on a volume conductivity of 62%. 



Copyright © 2004 IEEE. All rights reserved. 



23 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



For other winding materials, a suitable value of k\ (inferred temperature for zero resistance) shall be used. 

The temperature obtained by using Equation (26) is the total temperature of the winding at the time of the 
test. If this is the usable shutdown resistance reading, the results will be the total temperature of the winding 
at the test ambient temperature. If this ambient differs from the reference ambient, see 3.3.1, adjust the total 
temperature by subtracting the test ambient from the calculated total temperature and then adding 25 °C to 
the difference value just obtained. If the temperature test was at the rated load, the resultant sum is the total 
winding temperature in a 25 °C ambient and is the specified temperature to be used in the efficiency 
analysis. See 3.3.2 a), if the test was at other than rated load, see 5.8.4 for the procedure to correct to rated 
load. 

5.9 Equivalent circuit 

The operating characteristics in Efficiency Test Methods F and Fl (see 6.9) are calculated based on the 
equivalent circuit of an induction machine shown in Figure 2. This circuit is also used in determining the 
rotor current used in determining the stray -load losses used in other efficiency test methods. 




Figure 2 — Equivalent circuit 



The machine quantities associated with the equivalent circuit and with Equation (27) through Equation (58) 
are as follows: 



V\ is phase voltage, in V 

Vi is rotor phase voltage referred to the stator, in V 

/' is frequency, in Hz 

I\ is line or stator current, in A 

h is rotor current referred to stator, in A 

I m is magnetizing current, in A 

If e is core loss current, in A 

m is number of phases 

R\ is stator resistance, in ohms 

Ih is rotor resistance referred to stator, in ohms 

Rf e is core loss resistance, in ohms 

Gf e is core loss conductance, in Siemens 

X\ is stator leakage reactance, in ohms 

X2 is rotor leakage reactance referred to stator, in ohms 



24 



Copyright © 2004 IEEE. All rights reserved. 



!EEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 12-2004 

Xm is magnetizing reactance, in ohms 

Bm is magnetizing susceptance, in Siemens 

P is power, in watts 

Ph is core loss, in watts 

Pf is friction and windage loss, in watts 

Q is reactive power, in vars 

Z is impedance per phase, in ohms 

Z2 is rotor impedance per phase referred to stator, in ohms 

s is slip in p. u. 



Subscripts are as follows: 

= quantities pertaining to no-load 

L = quantities pertaining to impedance test 

NOTES: 

1 —For three-phase machines, the per phase wye stator resistance is one-half of the terminal-to-terminal resistance. 

2— For three-phase machines, the wye phase voltage, V } , is the line-to-line voltage divided by J 3 . 

The machine parameters in the equivalent circuit are derived from test data recorded during a no-load test of 
5.5 and one of the impedance tests described in 5.9.1 . The equivalent circuit represents one phase of a three- 
phase, wye-connected machine and is usable even if the machine under test has a delta internal connection. 
Rotor voltage, current, resistance, and reactance values all are referred to the stator and are not true rotor 
values but can be used throughout this standard wherever rotor parameters are specified. 

Accurate prediction of machine characteristics in the normal operating range will depend primarily upon the 
closeness by which R2 represents the actual rotor resistance to currents of low frequency and, secondarily, 
upon the closeness by which X2 represents the actual rotor leakage reactance to currents of low frequency. 
Therefore, the most careful procedure during testing to determine the rotor characteristics at low frequency 
is imperative. Calculation results may be reported on Form 9.14. 

5.9.1 Impedance tests 

Readings of voltage, current, electrical input power, and stator resistance or stator winding temperature are 
to be taken at one or more frequencies, voltages, and/or loads. These data are referred to as the impedance 
data. If the machine being tested has a wound rotor, the rotor is to be short-circuited for the test. 

The tests for reactance shall be conducted at rated load current. It is important that the value of reactance 
used in the equivalent circuit calculation is at the correct value of saturation and deep bar effect; otherwise, 
the calculated power factor will be found to be higher than the true value. The reactance and impedance shall 
be determined at the temperature of the machine at the time of the test. Resistance values shall be corrected 
to the specified temperature before being reported as an equivalent circuit parameter. 

The impedance data shall be determined from one of the following methods: 

a) Method 1 —A three-phase locked-rotor impedance test at maximum of 25% of rated frequency and 
at rated current. See 5.9.2 for details. 

b) Method 2— Three-phase locked-rotor impedance tests at three frequencies; one at rated frequency, 
one at approximately 50% of rated frequency, and one at a maximum of 25% of rated frequency, all 
at rated current. Curves shall be developed from these three test points and used to determine the 
values of total reactance and rotor resistance at the required reduced frequency. See 5.9.3 for details. 



Copyright © 2004 IEEE. All rights reserved. 25 



IEEE 

Std 11 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

c) Method J— An impedance test at a slip speed approximating the desired reduced rotor frequency. In 
this method, the motor is run uncoupled or coupled to a reduced load, and the voltage is reduced to 
give approximately full load slip point/ The slip shall be measured carefully. See 5.9.4 for details. 

d) Method 4— When none of the previous methods is practical, the following test may be utilized: a 
three-phase, locked-rotor impedance test at reduced voltage at rated frequency resulting in approxi- 
mately rated current and a test under load. See 5.9.5 for details. 

5.9.2 Calculation of parameters— Method 1 

5.9.2.1 Locked rotor test 

The rotor of a squirrel -cage motor is a symmetrical bar winding; therefore, the impedance of the motor is 
practically the same for any position of the rotor relative in the stator. 

The impedance of a wound-rotor motor varies with the position of the rotor relative to the stator. It is 
therefore necessary when performing a locked-rotor impedance test to determine the rotor position that 
results in an average value of impedance. Before taking readings on wound-rotor machines, the rotor shall 
be short-circuited. The angular distance through which it is necessary to observe the current variation shall 
be determined by allowing the rotor to revolve slowly and observing the stator current, noting the distance 
the rotor must move for the stator current to complete a cycle. For machines having an integral number of 
slots per pole per phase in both rotor and stator, this distance will be equal to two- thirds of a pole pitch for 
three-phase machines. For machines having fractional slot windings, the angular distance may be as much 
as a full pole pitch. 

The rotor of a wound-rotor motor shall be blocked so that it cannot rotate freely, but can be moved; and the 
impressed voltage shall be increased gradually until a current of approximately rated value is obtained. 
Voltage and current on all phases shall be read and recorded, and the voltage in the different phases shall be 
balanced. Holding the same voltage, the rotor shall be turned slowly and the minimum and maximum values 
of current during a complete cycle shall be recorded. The rotor shall then be blocked for the impedance test 
on the position that gives a current equal to the average of the minimum and maximum values previously 
recorded. 

For the locked-rotor test, take simultaneous readings of voltage and current in all phases and of power input 
at several levels of voltage in order to establish the value with special care in the neighborhood of full-load 
current. The stator winding temperature or stator winding resistance shall also be recorded. Care shall be 
taken not to overheat the windings. Taking the highest readings first and the lower readings in succession 
will help to equalize the temperature. 

5.9.2.2 Calculations 

Plot curves using volts as abscissas and the amperes and the input power as ordinates. The curve of amperes 
vs. volts is usually a straight line, curving slightly upward at the higher values. On closed slot rotors, 
however, there is also a distinct curve upward at low voltage. Derive the value of voltage and power input to 
determine the total reactance and rotor resistance at the required level of current from these curves. 

Determine the rotor resistance, /?2, and the total leakage reactance, X\ + Xn, from these data using the 
Equation (27) through Equation (38). The calculations start by assuming a relationship between X\ and X%. 
When design details are available, use the calculated ratio X\IX2- Otherwise, use 



7 This test is described herein as being run at a reduced voltage. This is because it is recognized that when using the more readily avail- 
able small loading devices, a reduced voltage must be used to obtain the required full load slip test point. With suitable loading, this test 
may be performed at higher voltages; up to and including rated voltage. 



26 Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



X, 



~ l .0 for Design A, Design D, and wound rotor motors 



= 0.67 for Design B motors 



x, 



y\ =0.43 for Design C motors 



NOTE-Design A, BX, and D motors are defined in NEMA MG- 1-2003 [B3]. 

Calculate the reactive power of complete motor at no load, Qo, and at the conditions of the impedance test, 
Ql- 



<2o = J(mVM 2 -PS 



(27) 



and 



Ql = ^rnV x J XL Y-P\ (28) 

The per phase voltage, V] , as used in Equation (27) and Equation (28) for a three phase machine is 



T/ _ Line-to-Line voltage 
v \ - r 

ft 



(29) 



See Figure 2 for identification of the quantities and subscripts in the above and in the following equations. 
Calculate the magnetizing reactance Xm- 



Xm ~ 



m V\ i 
u x 






v xj 

Calculate the stator leakage reactance X\ at test frequency. 



X\L = 



Ql 



\( x \\ x \ 



mf- L x 



W^W*' 1 



x 2 i X M . 



_\x 2 J x M _ 



Determine the stator leakage reactance at rated frequency. 

x, = L xjf 1L 

JL 

Equation (30), Equation (31), and Equation (32) may be solved as follows: 

1) Solve Equation (30) for Xm, assuming a value of X\/Xm and X\ 

2) Solve Equation (31) for X\l, using the same value of X\/Xm as above 



(30) 



(31) 



(32) 



Copyright © 2004 IEEE. Ail rights reserved. 



27 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

3) Solve Equation (32) for X\ 

4) Solve Equation (30) for Xm, using X\ from Equation (32) and a ratio of X\IXm from Equation (30) 
and Equation (32) 

5) Continue iteration solution until stable values of X\ and X^f are obtained within 0.1% 

B M = y- (33) 






X 2L = ^±- (34) 



® 



A 



X 2 = jrxX 2L (35) 



G A x (i + ^) 2 (36) 

/l mV] Q \ Xj 

where 
Ph is the total core loss, in W, as determined in 5.5.5. 

(37) 



Rfe 


= 


1 
G fe 


RlL 


= 


W? # 



't-**)"{>+%)'-fjd'*<xM m 

where 

R]L is equal to 1/2 of the line-to-line stator winding resistance, in ohms, at test temperature. 

Correct R\i and i?2L to the specified temperature using Equation (3) and identify as R\ and Ri- 

5.9.3 Calculation of parameters— Method 2 

When using Method 2, perform the tests in 5.9.1 and use the calculation procedure in 5.9.2.2 to find the rotor 
resistance, R21 and total leakage reactance, X\i + X^l, at each of the three frequencies. Develop curves of 
the values of rotor resistance and total leakage reactance vs. frequency that can be used to determine the val- 
ues at the required reduced operating frequency. The resulting value for rotor resistance and the values for 
leakage inductances, after conversion to operating frequency, are then used in the equivalent circuit to deter- 
mine machine performance. 

5.9.4 Calculation of parameters— Method 3 

5.9.4.1 Reduced voltage slip test 

The rotor resistance, R2, and the leakage reactance, A'2, at reduced frequency may be obtained from readings 
(volts, watts, amperes, slip, stator winding temperature or stator winding resistance) at a slip speed 
approximating the desired reduced rotor frequency. In this method, the machine is run uncoupled or coupled 
to a reduced load and at a voltage that gives desired slip speed. A generator can be operated as a motor or 

28 Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



to a reduced load and at a voltage that gives desired slip speed. A generator can be operated as a motor or 
can be coupled to driving equipment at a speed above synchronous speed that gives the desired slip while at 
a reduced voltage to reduce the electrical output. The slip shall be measured very carefully. 

5.9.4.2 Calculations 

With data from the no-load saturation test, see 5.5, calculate the total reactance per phase for each test point 
and draw a curve of total reactance per phase vs. no-load volts per phase. See example in Figure 3. The high- 
est point on this curve is used as the total no-load reactance per phase, X\ + Xm, in calculations of the 
reduced voltage slip test. 



CD 


/ 


F 




D 




C/) 






















C 


O. 




G / 








s— 


/ 










CD 












Q_ 












—^ 












A 
























CD 












O 












c 












03 












CD 




E 








CD 












S_ 












2 






B 




, A 


O 






A 




A 



Volts per phase 



Figure 3— Total reactance from no load test 



Quantities associated with Figure 3 are as follows: 

A is rated volts. 

B is volts at reduced voltage slip test. 

CDE is curve of total reactance from no-load test. 

F is reactance corresponding to the highest point, D, of the test curve CDE. This value is used as the 

total reactance, X x + X M , in calculations of the reduced voltage slip test. 

G is total reactance, X] + X M , to be used in determining X M for use in the equivalent circuit calcula- 
tions after X { , X 2 , and R 2 are determined from the calculations of the reduced voltage test. 

If the machine was operated as a motor in performing the reduced voltage slip test then the measured 
electrical power when used in the calculations should be specified as having a positive value. If the machine 
was tested as a generator, the measured electrical power used in the calculations is specified as having a 
negative value, since it is opposite in direction to the power flow as illustrated in Figure 2. From the reduced 
voltage slip test data, calculate the total impedance per phase, Z and the power factor, Pf\ (which will be 
negative for generator operation). The phase angle, 8|, of the input current, the total apparent resistance per 
phase, R y and the total apparent reactance per phase, X, can be found as shown in Equation (39) through 
Equation (41): 



1 = -arc cos (PF) 
R - Zxcos(~9 1 ) 
X ^ Zx sin(-ej) 



(39) 
(40) 
(41) 



Copyright © 2004 IEEE. All rights reserved. 



29 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

The value of X determined from Equation (41) is used as a first estimate for the sum (X\ + Xj). A value for 
the ratio {X\iXi) is obtained from design details, when known, or from 5.9.2.2. Based on this sum and ratio 
an initial estimate for the value of X\ can be calculated as shown in Equation (42). 



© 



A', = X '— (42) 

'♦© 

Using the value of total no-load reactance, (X\ + Xm)> from point D of Figure 3, the value of the magnetizing 
reactance, Xm, can be approximated as shown in Equation (43). 

X M = (X X +X M )-X X (43) 

From the data obtained from the reduced voltage slip test, calculate 



V 2 - 7[ F i-A(^i cos0 i- Ar i sin9 i)] 2 + [ / i( /? ] sine i + ^i cos 9i)] 2 (44) 

The resistance, R h shall be corrected to the temperature during the test before use in Equation (44) and in 
following equations. 

When calculating the phase angle 02, the value is that for the quadrant associated with the signs of the values 
of the numerator and denominator terms in Equation (45), 

6. = arctan L1 ~ J ! ] ^~~ (45) 

V x -l x (R x cose^^sine,) 

K = y (46) 

V 2 
R fe = -± (47) 

It h 



G fe = ~- (48) 

R fe 
he = if ( 49 ) 



Calculate 

I 2 - a/[/jCOs0| -/ c sin8 2 -/^cos9 2 ] + [--/j sin0 1 +/ e cos8 2 + /^sin0 2 ]" 



(50) 



x 2 = -y«™*>-M-' 2 .x» (51) 

X = X } +X 2 (52) 



30 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

Repeat Equation (42) through Equation (52) using the initial ratio of X\ 1 X 2 as used in Equation (42) and the 
new value of X from Equation (52) and continue until stable values of X\ and X 2 are achieved within 0.1%. 

Z 2 = h (53) 

1 2 



R 2 = sjizpif) (54) 

Then, using the value of total reactance, (X| + Xm), from the rated voltage no-load test point C in Figure 3, 
calculate 

X M = (X,+X M )-X l (55) 

B M = f (56) 



V 2 = ^[Fj-Z^^^ose^^sine^^ + ^^jsine^^cose,)] 2 (57) 

o fe - -^ (58) 

The values obtained in Equation (39), Equation (51), Equation (56), and Equation (58) are used in the 
equivalent circuit calculations. The rotor resistance, R 2 , from Equation (54) and stator resistance, R\, shall 
be corrected to the specified temperature using Equation (3) before being used in the equivalent circuit. 

5.9.5 Calculation of parameters— Method 4 

5.9.5.1 Locked-rotor and load point test 

The following tests at rated frequency are required: 

a) No-load test per 5 .5 . 

b) Locked-rotor test at reduced voltage following the procedure in 5.9 .2. 1 . 

c) Operating the machine uncoupled (or coupled to some reduced load) with the voltage reduced to 
give approximately full-load slip. The slip must be determined very carefully. 

For each test, record the volts, watts, amperes, slip, and stator winding resistance or stator winding 
temperature. 

5.9.5.2 Calculations 

The values of X\, X 2 , Xm, and Rf e are determined from the no-load and locked-rotor tests at rated frequency 
following the procedure in 5.9.2. The value of R 2 at reduced frequency is obtained from the test data 
recorded for operation at approximately full-load slip. The full-load slip is determined using nameplate 
speed or design data. 

After X\ has been determined from the locked-rotor impedance tests, see 5.9.2.2, the value of R 2 is obtained 
from the full-load slip test as follows: 

-— Calculate V? using Equation (44). 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

— Calculate 02 using Equation (45). 

— Calculate if e and I e using Equation (49) and Equation (46). 

— Calculate h using Equation (50). 

— Calculate rotor impedance, Zi using Equation (53). 

Calculate Ri using Equation (54) and correct to the specified temperature using Equation (3). 

5.10 Brush-contact loss 

This measurement is used in efficiency methods F and Fl (see 6.8). For wound-rotor machines, the brush 
contact loss is determined by the product of the calculated secondary current and a voltage drop. The voltage 
drop in all brushes of the same phase (between rings on a three-ring machine) may be assumed to be 1.0 V 
for carbon or graphite brushes, and 0.3 V for metal-carbon brushes. 

5.11 Power factor 

5.11.1 Indirectly obtained 

When determining the machine performance characteristics, the power factor of the machine shall be 
determined for each load point using Equation (59). 

PF - f (59) 

J3 x VI 

where 

P is the machine electrical power, in W. input for a motor or output for a generator, 

PF is the machine power factor, 

V is input, line-to-line voltage, in volts, 

/ is input current, in A. 

NOTE — The power factor, PF, obtained with Equation (59) is a numeric value, i.e., 0.x x. To obtain in percent form, 
multiply the numeric value by 100. 

5.11.2 Directly obtained 

When using the two- wattmeter method to measure input power of three-phase machines, the power factor, 
PF, in percent, may be checked by Equation (60). 

PF - lQ0 — (60) 

n + ir-"*' 



where 

P\ is the higher reading, 
Pn is the lower reading. 

If the wattmeter for the Pn reading gives a negative reading, it shall be considered a negative quantity. 

If a polyphase wattmeter is used, the values of the two- wattmeter readings can be obtained by opening 
separately each of the voltage coil circuits of the polyphase wattmeter. 

32 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 12-2004 

With pulsating loads, the power factor obtained by the direct method may be higher than that obtained by the 
indirect method. The higher value shall be taken as the correct reading. The difference is due to the inclusion 
in the volt-amperes of the pulsating component of current, which is a function of the load rather than of the 
machine itself. The power factor determined from the ratio of wattmeter readings is not affected by the pres- 
ence of pulsating current. 

5.11.3 Equivalent circuit calculation 

The power factor, in percent, may be determined from the equivalent circuit by multiplying the total 
resistance by 100 and then dividing the result by the total impedance. 



6. Determination of efficiency 

6.1 General 

Efficiency is the ratio of output power to total input power. Output power is equal to input power minus the 
losses. Therefore, if two of the three variables (output, input, or losses) are known, the efficiency can be 
determined by using Equation (61), Equation (62), or Equation (63). 

efficiency = output power (6]) 

input power 

A form commonly used for motors is: 

efficiency = i"P"t power - losses (62) 

input power 

A form commonly used for generators is: 

efficiency = output power (63) 

output power + losses 

Unless otherwise specified, the efficiency shall be determined for rated voltage and frequency. When a load 
point is available at other than rated voltage, it may be combined with the equivalent circuit (Methods F and 
Fl) to calculate the performance at rated voltage (see 6.9). 

6.2 Efficiency test methods 

The various methods of efficiency and loss determination are identified as follows: 

a) Method A Input-output 

b) Method B Input-output with segregation of losses and indirect measurement of stray -load loss 

c) Method Bl Input-output with segregation of losses, indirect measurement of stray-load loss and 

an assumed temperature 

d) Method C Duplicate machines with segregation of losses and indirect measurement of stray- load 

loss 

e) Method E Electric power measurement under load with segregation of losses and direct 

measurement of stray-load loss 



Copyright © 2004 IEEE. AN rights reserved. 33 



IEEE 

Std 1 12-2004 IEEE STANDARD TEST PROCEDURE FOR 

f) Method El Electric power measurement under load with segregation of losses and assumed 

value of stray-load loss 

g) Method. F Equivalent circuit with direct measurement of stray-load loss 

h) Method Fl Equivalent circuit with assumed value of stray-load loss 

i) Method C/F Equivalent circuit calibrated per Method C load point with indirect measurement of 
stray-load loss 

j) Method E/F Equivalent circuit calibrated per Method E load point with direct measurement of 
stray-load loss 

k) Method El /Fl Equivalent circuit calibrated per Method E load point with assumed value of stray- 
load loss 

6.2.1 Guide for choice of efficiency test method 

The input-output method (Efficiency Test Method A) should be limited to machines with ratings less than 
l kW. 

Horizontal machines rated at 1-300 kW should be tested using Efficiency Test Method B, the input-output 
method with loss segregation. 

Vertical machines in the range of 1-300 kW should be tested by Efficiency Test Method B if the machine 
bearing construction permits. If the bearing construction does not permit Method B testing, Method E, El , 
F, or Fl may be used. 

Machines rated higher than 300 kW should be tested by Efficiency Test Method B, Bl, C, E, El, F, or Fl 
depending on the capability of the test facility. When proper test facilities are available, Method B should be 
selected when the precision and repeatability of this method is required. 

When practical, load test calibration of the equivalent circuit (Efficiency Test Method C/F, E/F, or El/Fl) 
provides the confidence level of a full -load test with the simplicity of determining performance at various 
loads by solution of the equivalent circuit. 

6.3 Efficiency Test Method A— Input-output 

For this method, the efficiency is calculated as the ratio of the measured output power to the measured input 
power, after temperature and dynamometer corrections, if applicable. 

6.3.1 Test procedure 

6.3.1.1 Cold resistance 

With the machine at ambient temperature, measure and record the winding(s) resistances and the ambient 
temperature. See 5.4. 

6.3.1.2 Rated load temperature test 

Perform a rated load temperature test in accordance with 5.8.3.1 . 

6.3.1.3 Test under load 

The machine is loaded by means of a mechanical brake or dynamometer. See 5.6.1 . 



34 Copyright © 2004 iEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

6.3.1.4 Calculations 

Performance is calculated as shown in Form A in 9.2 with details of the calculations shown in Form A2 in 
9.3. Dynamometer correction should be made, if applicable, as shown in 5.6.1.2. The stator I 2 R loss and the 
slip are to be corrected for temperature as indicated. 

6.3.1.5 Temperature correction 

The stator power is corrected to the specified temperature. The amount of power correction required is 
determined by Equation (64). 



p _ [2 R „J2 R (64) 

where 



P c is the necessary power correction, in W, 

I t is the line current, in A, during the test, 

R t is the average winding resistance, in ohms, at shutdown, 

R s is Rj corrected to the specified temperature, see Equation (3). 

The corrected stator power for a motor is the measured electrical power during the test plus P c . The 
corrected stator power for a generator is the measured electrical power during the test minus P c . 

The measured slip is corrected to the specified temperature using Equation (9) in 53.2. 

6.3.2 Efficiency 

Use the corrected electrical and the mechanical power values to calculate efficiencies. See 6.1 . 

6.4 Efficiency Test Method B- Input-output with loss segregation 

All data are taken with the machine operating either as a motor or as a generator, depending upon the region 
of operation for which the efficiency data are required. The apparent total loss (input minus output) is 
segregated into its various components with stray-load loss defined as the difference between the apparent 
total loss and the sum of the conventional losses (stator and rotor P-R loss, core loss, and friction and 
windage loss). The value of stray-load loss thus determined is plotted vs. torque squared, and a linear 
regression is used to reduce the effect of random errors in the test measurements. The smoothed stray-load 
loss data are used to calculate the final value of total loss and the efficiency. 

6.4.1 Test procedure 

The individual tests that make up the Method B test method shall be performed in the order listed. It is not 
necessary that these tests be performed in time succession with each immediately following the previous 
one. The tests may be performed individually if the operating temperature of the machine is established 
close to its normal operating temperature for the type of test prior to obtaining the test data. 

6.4.1.1 Cold resistance 

With the machine at ambient temperature, measure and record the winding(s) resistances and the ambient 
temperature. See 5.4. 



Copyright © 2004 IEEE. All rights reserved. 35 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.4.1.2 Rated load temperature test 

A rated load temperature test, using a dynamometer, is to be performed in accordance with 5.8.3.1 . This test 
is not required when a rated load temperature test had previously been performed on a duplicate machine. 
Determine the specified temperature for the machine. See 3.3.2 a) or b). 

6.4.1.3 Test under load 

During this test, the machine shall be loaded by a dynamometer, see 5.6.1. The temperature of the stator 
winding shall be within 10 °C of the hottest temperature reading recorded during the rated load temperature 
test on this or the duplicate machine prior to the start of recording data for this test. Perform the test as 
quickly as possible to minimize temperature changes in the machine during testing. When necessary, a 
dynamometer correction test shall be made. See 5.6.1.2. 

6.4.1.4 No-load test 

Perform a no-load test in accordance with 5.5 and 5.5.1 . 
6.4.2 Calculations 

6.4.2.1 Calculation form 

Calculate motor or generator performance using Form B in 9.4 as a guide. The source of each of the items on 
Form B or the method of its calculation is shown on Form B2 in 9.5. 

6.4.2.2 Friction and windage loss 

See 5.5.4. 

6.4.2.3 Core loss 
See 5.5.5. 

6.4.2.4 Stator l 2 R loss 

See 5.2. 

This calculation of stator PR losses for each load point shall be accomplished using the average winding 
resistance. If the average winding resistance is measured at each point during the load test, it can be directly 
used in the determination of the stator PR loss at that load point. If the winding temperature is obtained by 
means of local or embedded detectors, these readings shall be converted into an equivalent average value 
before performing the loss calculations. 

From the rated load temperature test of 6.4.1.2, obtain the winding resistance at shutdown and the 
temperature at shutdown by both the winding resistance and by local detector. This should be the same local 
detector being used during the load test. A value closely approximating the average temperature can then be 
determined by Equation (65). 

1 a = : — (6:>) 

'TTD 

where 



36 Copyright © 2004 IEEE. Al! rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 12-2004 

tj\ is the developed average temperature, in °C, for use in the loss calculations, 

tjR is the total temperature, in °C, from the shut down of the temperature test, 

t t is the temperature, in °C, by detector during the load test, 

trro » s the temperature, in °C, by detector from the shutdown of the temperature test. 

The average resistance to be used for the stator RR loss can be determined by Equation (3) using Itr - hi, 
Ia - t} ? and R a equal to the resistance value at temperature test shutdown. This calculation procedure is 
repeated for each load point. 

6.4.2.5 Rotor i 2 R loss 

See 5.3. The first calculation of rotor PR loss is based on actual speed or slip measurement for each point 
and no adjustments are required. 

6.4.2.6 Apparent total loss 

The apparent total loss shall be calculated separately for each load point by subtracting the measured output 
in watts from the measured input in watts. 

6.4.2.7 Stray-load loss determination (indirect method) 

The stray-load loss shall be separately calculated for each load point by subtracting from the apparent total 
loss the stator PR loss at the temperature of the test, the core loss, the friction and windage loss, and the rotor 
PR loss corresponding to the measured value of slip. 

6.4.2.8 Smoothing of the stray-load loss 

Smooth the stray-load loss data by using a linear regression analysis based on expressing the stray-load loss 
as a function of the square of the load torque. The results of the analysis should be as shown in 
Equation (66). 

P SL = Af + B (66) 

where 

Psl is the stray-load loss, in W, as plotted vs. torque squared, 

T is the torque, in N*m, 

A is the slope, 

B is the intercept with the zero torque line. 

If the slope is negative, or if the correlation factor is less than 0.9, delete the worst point and repeat the 
regression analysis. If this increases the correlation factor to 0.9 or larger, use the second regression; if not, 
or if the slope is still negative, the test is unsatisfactory. Errors in the instrumentation or test readings, or 
both, are indicated. The source of the error should be investigated and corrected, and the test under load, see 
6.4.1 .3. should be repeated. 

Copyright © 2004 IEEE. All rights reserved. 37 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.4.3 Corrections 

6.4.3.1 Corrected stray-load loss 

The stray-load loss curve of 6.4.2.8 is corrected by shifting the curve to go through the origin while 
maintaining the original slope. The result of this correction is Equation (67), which is used to determine the 
corrected value of stray -load loss, Pslc* f° r eacn J° a d point. 

Pslc^A? (67) 

where 

A is the slope of the of the Psl v $- T 1 curve defined in 6.4.2.8, 

T is the torque, in N-m, for each load point as used in 6.4.2.8. 

6.4.3.2 Temperature correction of stator l 2 R loss 

A corrected stator PR loss for each of the load points is calculated using the average stator resistance 
corrected to the specified temperature. Using resistance and the total temperature, by resistance, at shutdown 
from 6,4.1 .2, correct this resistance to the specified temperature using Equation (3). Calculate the loss as in 

5.2. 

6.4.3.3 Temperature correction of rotor l 2 R loss 

A corrected rotor PR loss for each of the load points is calculated as in 5.3, Equation (4) or Equation (5), 
using the value of slip for each of the points corrected to the specified temperature, using Equation (9), and 
using the corrected value of the stator I 2 R loss, from 6.4.3.2, for each load point. The slip used in 
Equation (4) or Equation (5), is the slip used in 6.4.2.5 corrected to the specified temperature from the 
developed average temperature from 6.4.2.4. 

6.4.3.4 Corrected total loss 

A corrected total loss for each of the load points is determined as the sum of the friction and windage loss 
(see 6.4.2.2), the core loss (see 6.4.2.3), the corrected stray-load loss (see 6.4.3.1), the corrected stator I 2 R 
loss (see 6.4.3.2), and the corrected rotor fiR loss (see 6.4.3.3). 

6.4.3.5 Corrected mechanical power 

The corrected mechanical (output) power for each of the load points for a motor is equal to the difference 
between the measured electrical (input) power and the corrected total loss. The corrected mechanical (input) 
power for a generator is equal to the sum of the measured electrical (output) power and the corrected total 
loss. 

6.4.4 Efficiency 

Use the measured electrical power and the corrected mechanical power to calculate efficiency. See 6.1 . 

6.4.5 Power factor 

The power factor of the machine shall be determined for each load point using Equation (59). See 5.11. 

38 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

6.4.6 Summary of characteristics 

The summary of characteristics is a listing of the power factor, the efficiency, the speed, and the line current 
at precise load points. To obtain this information, plot the values from the analysis for the line current, 
speed, and efficiency vs. the output power. Fit curves to these data and pick off the values for the desired 
load points. The power factor is computed for each precise load point from its amperes, volts, and input 
watts as in Equation (59). 

This summary of machine characteristics is included in Form B. See 9.4. 

6.5 Efficiency Test Method B1 —Input-output with loss segregation and assumed 
temperature 

All data are taken with the machine operating either as a motor or as a generator, depending upon the region 
of operation for which the efficiency data are required. The apparent total loss (input minus output) is 
segregated into its various components with stray-load loss defined as the difference between the apparent 
total loss and the sum of the conventional losses (stator and rotor P-R loss, core loss, and friction and 
windage loss). The value of stray-load loss thus determined is plotted vs. torque squared, and a linear 
regression is used to reduce the effect of random errors in the test measurements. The smoothed stray-load 
loss data are used to calculate the final value of total loss and the efficiency. 

6.5.1 Test procedure 

The individual tests that make up the Method Bl test method shall be performed in the order listed. It is not 
necessary that these tests be performed in time succession with each immediately following the previous 
one. The tests may be performed individually if the operating temperature of the motor is established close 
to its normal operating temperature for the type of test prior to obtaining the test data. 

6.5.1.1 Cold resistance 

With the machine at ambient temperature, measure and record the winding(s) resistances and the ambient 
temperature. See 5.4. 

6.5.1.2 Temperature 

A load test to determine temperature rise and total temperature is not performed in Efficiency Test Method 
Bl . The specified temperature is determined as in 3.3.2 c). 

6.5.1.3 No-load test 

Perform a no-load test in accordance with 5.5 including the bearing loss stabilization step of 5.5.1 . 

6.5.1.4 Test under load 

For this test, the machine shall be loaded by a dynamometer, see 5.6.1. The temperature of the stator 
winding shall be within 10 °C of the specified temperature, as selected in 6.5.1.2. prior to the start of 
recording data for this test. Perform the test as quickly as possible to minimize temperature changes in the 
machine during testing. When necessary, a dynamometer correction test shall be made. See 5.6.1 ,2. 



Copyright © 2004 IEEE. All rights reserved. 39 



IEEE 

Std 11 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.5.2 Calculations 

6.5.2.1 Calculation form 

Calculate motor or generator performance using Form Bl in 9.6 as a guide. The source of each of the items 
on Form B 1 or the method of its calculation is shown on Form Bl-2 in 9.7. 

6.5.2.2 Friction and windage loss 

See 5.5.4. 

6.5.2.3 Core loss 

See 5.5.5. 

6.5.2.4 Stator l 2 R loss 

See 5.2. Calculate loss with winding resistance corrected to the test temperature. 

6.5.2.5 Rotor l 2 R loss 

See 5.3. This first calculation of rotor fiR loss is based on actual speed or slip measurement for each point 
and no adjustments are required. 

6.5.2.6 Apparent total loss 

The apparent total loss shall be calculated separately for each load point by subtracting the measured output 
in watts from the measured input in watts. 

6.5.2.7 Stray-load loss determination (indirect method) 

6.5.2.8 Smoothing of the stray-load loss 

The stray-load loss shall be separately calculated for each load point by subtracting from the apparent total 
loss the stator I 2 R loss at the temperature of the test, the core loss, the friction and windage loss, and the rotor 
PR loss corresponding to the measured value of slip. 

Smooth the stray -load loss data by using a linear regression analysis based on expressing the stray-load loss 
as a function of the square of the load torque. The results of the analysis should be as shown in Equation (66) 
in 6.4.2.8. 

If this analysis shows the slope as negative, or if the correlation factor is less than 0.9, delete the worst point 
and repeat the regression analysis. If this increases the correlation factor to 0.9 or larger, use the second 
regression; if not, or if the slope is still negative, the test is unsatisfactory. Errors in the instrumentation or 
test readings, or both, are indicated. The source of the error should be investigated and corrected, and the test 
under load, see 6.5.1 .4, should be repeated. 

6.5.3 Corrections 

6.5.3.1 Corrected stray-load loss 

The corrected value of stray-load loss, Psic is determined using Equation (67) with T equal to the torque for 
each of the load points and A is the slope of the function curve as determined in 6.5.2.8. 

40 Copyright © 2004 IEEE. Alt rights reserved. 



iEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 12-2004 

6.5.3.2 Temperature correction of stator l 2 R loss 

A corrected stator PR loss for each of the load points is calculated using the average cold stator resistance 
from 6.5.1 .1 corrected to the specified temperature. Calculate the loss as in 5.2. 

6.5.3.3 Temperature correction of rotor l 2 R loss 

A corrected rotor PR loss for each of the load points is calculated as in 53, Equation (4) or Equation (5), 
using the value of slip for each of the points corrected to the specified temperature, using Equation (9), and 
using the corrected value of the stator PR loss, from 6.5.3.2, for each load point. The slip used in 
Equation (4) or Equation (5), is the slip used in 6.5.2.5 corrected to the specified temperature from the test 
temperature at the applicable test point. 

6.5.3.4 Corrected total loss 

A corrected total loss for each of the load points is determined as the sum of the friction and windage loss 
(see 6.5.2.2), the core loss (see 6.5.23), the corrected stray-load loss (see 6.5.3.1), the corrected stator PR 
loss (see 6.5.3.2), and the corrected rotor PR loss (see 6.5.3.3). 

6.5.3.5 Corrected mechanical power 

The corrected mechanical (output) power for each of the load points for a motor is equal to the difference of 
the measured electrical (input) power and the corrected total loss. The corrected mechanical (input) power 
for a generator is equal to the sum of the measured electrical (output) power and the corrected total loss. 

6.5.4 Efficiency 

Use the measured electrical power and the corrected mechanical power to calculate efficiency. See 6.1. 

6.5.5 Power factor 

The power factor of the machine shall be determined for each load point using Equation (59) of 5.1 1 . 

6.5.6 Summary of characteristics 

The summary of characteristics is a listing of the power factor, the efficiency, the speed, and the line current 
at precise load points. To obtain this information, plot the values from the analysis for the line current, 
speed, and efficiency vs, the output power. Fit curves to these data and pick off the values for the desired 
load points. The power factor is computed for each precise load point from its amperes, volts, and input 
watts as in Equation (59). 

This summary of machine characteristics is included in Form Bl . See 9.6. 

6.6 Efficiency Test Method C-Duplicate machines 

This method of determining efficiency may be used when duplicate machines are available. The two 
machines are coupled together and electrically connected to two sources of power, the frequency of one 
being adjustable. Both power supplies must meet the requirements of 3.1 2 and 3.1 .3 and must be capable of 
power delivery and power absorption. The stray -load loss is determined by the indirect method. 

Copyright © 2004 IEEE. All rights reserved. 4 1 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.6.1 Test procedure 

The individual tests that make up the Method C efficiency test shall be performed in the order listed. It is not 
necessary that these tests be performed in time succession with each immediately following the previous 
one. The tests may be performed individually if the operating temperatures of the machines are established 
close to their normal operating temperature for the type of test prior to obtaining the test data. 

For convenience in this analysis description, the machine connected to the constant rated frequency power 
supply during the load test is identified as machine Ml and the machine connected to the variable voltage, 
variable frequency supply is identified as machine M2. 

6.6.1.1 Cold resistance 

With the machines at ambient temperature, measure and record the winding(s) resistances of both machines 
and the ambient temperature. See 5.4. 

6.6.1.2 No-load tests of both machines 

Perform no-load tests on both machines. See 5.5. 

6.6.1.3 Test under load 

Couple the two machines together and arrange for machine Ml to be supplied from the rated frequency 
power supply and for machine M2 to operate from the variable power supply. Machine Ml shall be loaded 
as a motor and as a generator at line currents corresponding to four load points approximately equally spaced 
between not less than 25% and up to and including 100% load, and two load points suitably chosen above 
100% load but not exceeding 1 50% load. More load points may be used if desired. At each test point, obtain 
readings of electrical power, current, voltage, frequency, and stator winding temperature or stator winding 
resistance for both machines, along with speed and ambient temperature. 

The test should start at the highest load point with machine Ml operating as a motor. While maintaining 
rated voltage and frequency on machine Ml, decrease the frequency and voltage on machine M2 until the 
line current for machine Ml is approximately equal to that at the highest load point. When the voltage on 
machine M2 divided by the frequency of that voltage is equal to the rated voltage divided by rated fre- 
quency, this is a valid test point and the readings above should be obtained. 

Directly after obtaining the above readings, increase the frequency and voltage on machine M2 above rated 
frequency until the current on machine Ml, now operating as a generator, is the same as that recorded when 
machine Ml was operating as a motor. When the machine M2 voltage/frequency value is correct, this is a 
valid test point and the readings above should be obtained. 

The two sets of readings, with machine Ml operating as a motor and as a generator, complete the test data 
required for that load point. Then the test can proceed to the next test point and the data set with machine Ml 
acting as generator can be collected first. 

Continue in this manner takings readings for both directions of power flow until the sets of test data for all 
desired load points have been recorded. Perform this test as quickly as possible to minimize temperature 
changes in the machines during testing. 

When performing the first portion of the test at any load point, it is not necessary that the current be adjusted 
to precisely the predetermined current value; however, the current during the second portion of the test at 
that load point shall match that of the first as closely as the test equipment will permit. 



42 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

6.6.2 Calculations 

6.6.2.1 Calculation form 

Calculate the machine performance using Form C in 9.8 as a guide. Form C2 in 9.9 is provided to assist in 
understanding each item in the test and in the calculations. Take care in the organization of the data. The 
analysis requires the use of information and data from both machines in the calculations for both portions of 
each load point. Form C is arranged to present all these data in the proper sequence. 

6.6.2.2 Friction and windage 

See 5.5.4. 

6.6.2.3 Core loss 
See 5.5.5. 

6.6.2.4 Stator l 2 R loss 

See 5.2. 

The measured test temperature shall be used when adjusting the winding resistance for this loss determina- 
tion. The procedure for temperature refinement presented in 6.4.2.4 may be used if desired but only w r hen a 
full load temperature test has been performed on one of the machines. Two calculations for each machine 
are required for each load point, one during its motoring operation and the other during its generating 
operation. 

6.6.2.5 Rotor l 2 R loss 

See 5.3. This calculation is based on the actual speed or slip measurement for each portion of each point and 
no adjustments are required. Two calculations for each machine are required for each load point. Take care 
that the proper power flow is observed. Using the description of a load point test in 6.6.1 3, machine Ml is a 
motor and Equation (68) should be used while machine M2 is a generator and Equation (69) applies. For the 
second half of each point, this switches with Equation (69) being applied to machine Ml calculations and 
Equation (68) to machine M2 calculations. 

The motor rotor l"R loss is: 

motor rotor / R loss = motor slip x (motor input - stator J R loss - core loss) (68) 

Where the last quantity, motor input - stator l^R loss - core loss, is the power across the air gap of the motor 
and the motor slip, in p.u., is the observed slip or calculated from measured speed and frequency. 

The generator rotor 1 R loss is: 

generator rotor / R loss = generator slip x (generator output + stator / R loss + core loss) (69) 

Where the last quantity, generator output + stator I"R loss + core loss, is the power across the air gap of the 
generator and the generator slip, in p.u., is the observed slip or is as calculated from measured speed and 
frequency. 



Copyright © 2004 IEEE. All rights reserved. 43 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.6.2.6 Stray-load loss 

6.6.2.6.1 Machine M1 operating as a motor 

The combined stray -load loss is determined by subtracting from the total measured loss (the difference 
between input and output) the sum 
windage losses of the two machines. 



between input and output) the sum of the stator l 2 R losses, rotor l l R losses, core losses, and friction and 



The stray-load losses are assumed to be proportional to the square of the rotor current. The stray-load losses 
are as shown in Equation (70) and Equation (71). 

For machine Ml (as a motor): 

i,i . ,2 n i combined stray- load loss , nfXX 

motor stray- load loss = motor rotor / R loss x * (70) 

motor rotor I R + generator rotor FR loss 
For machine M2 (as a generator); 

generator load loss = (combined stray load loss) - (motor stray load loss) (71) 

6.6.2.6.2 Machine M1 operating as a generator 

Repeat the calculations of 6.4.2.4 through 6.4.2.6 with the reversed power flow. Machine M2 is now the 
motor and its stray-load loss is determined using Equation (70). Machine Ml is now the generator and its 
stray-load loss is determined using Equation (71). 

6.6.2.6.3 Averaging 

The preliminary value of the stray-load loss of machine Ml is the average of the two values determined for 
that machine in 6.6.2.6.1 and 6.6.2.6.2. The preliminary value of the stray-load loss of machine M2 is the 
average of the two values determined for that machine in 6.6.2.6.1 and 6.6.2.6.2. 

The average of these two preliminary values shall be considered the stray-load loss for use in the smoothing 
process described in 6.6.2.7. 

6.6.2.7 Smoothing of the stray-load loss 

Smooth the stray -load loss data from 6.6.2.6.3 by using a linear regression analysis based on expressing the 
stray-load loss as a function of the square of the rotor current. The results of the analysis should be as shown 
in Equation (72). 

PsLa Vg = W lavg ?+B (72) 

where 

PsLavs is the average value of stray-load loss, in W, as plotted vs. approximate rotor current squared, 

A is the slope, 

B is the intercept with the zero current line, 

havg |S the average value of rotor current, in amperes. 

The value of rotor current, I2, for each direction of power flow (motoring and generating) is as shown in 
Equation (73). 



44 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS std 1 12-2004 



(73) 



where 

/ is the observed value of stator line current, in amperes, (motoring or generating) for which 

stray-load loss is to be determined, 
/o is the value of no-load current, in amperes. 

If this analysis shows the slope as negative, or if the correlation factor is less than 0.9, delete the worst point 
and repeat the regression analysis. If this increases the correlation factor to 0.9 or larger, use the second 
regression; if not, or if the slope is still negative, the test is unsatisfactory. Errors in the instrumentation or 
test readings, or both, are indicated. The source of the error should be investigated and corrected, and the test 
under load, see 6.6.1 .3, should be repeated. 

6.6.3 Corrections 

The correction on stray-load loss could be applied to either machine; however, the corrections of other 
losses are performed on machine Ml. The performance of machine M2 could be determined in a similar 
manner if desired. 

6.6.3.1 Corrected stray-load loss 

The corrected value of stray-load loss is as shown in Equation (74). 

Psu = Mhf ™ 

where 

A is the slope of the of the P S i, vs. I 2 curve defined in 6.6.2.7, 

1 2 is the rotor current, in amperes, for each load point as used in 6.6.2.7. 

6.6.3.2 Temperature correction of stator l 2 R loss 

A corrected stator 1 2 R loss for each of the load points is calculated using the average stator resistance cor- 
rected to the specified temperature. If a full load temperature test was performed, use the total temperature, 
by resistance, at shutdown and correct the resistance taken at shutdown to the specified temperature using 
Equation (3). When no temperature test is performed, correct the cold resistance in 6.6.1 .1 to the specified 
temperature of 3.3.2 b) or 3.3.2 c), as applicable. Calculate the loss as in 5.2. 

6.6.3.3 Temperature correction of rotor l 2 R loss 

A corrected rotor I 2 R loss for each of the load points is calculated as in 5.3, Equation (4), using the value of 
slip for each of the points corrected to the specified temperature, using Equation (9), and using the corrected 
value of the stator I 2 R loss, from 6.6.3.2, for each load point. The slip used in Equation (4) or Equation (5), 
is the slip used in 6.6.2.5 corrected to the specified temperature. 

6.6.3.4 Corrected total loss 

A corrected total loss for each of the load points is determined as the sum of the friction and windage loss 
(see 6.6.2.2), the core loss (see 6.6.2.3), the corrected stray-load loss (see 6.6.3.1), the corrected stator 1"R 
loss (see 6.6.3,2). and the corrected rotor I 2 R loss (see 6.6.3.3). 

Copyright © 2004 IEEE. Ail rights reserved. 4i> 



IEEE 

Std 11 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.6.3.5 Corrected mechanical power 

The corrected mechanical (output) power for each of the load points for a motor is equal to the difference of 
the measured electrical (input) power and the corrected total loss. The corrected mechanical (input) power 
for a generator is equal to the sum of the measured electrical (output) power and the corrected total loss. 

6.6.4 Efficiency 

Use the measured electrical power and the corrected mechanical power to calculate efficiency. See 6A . 

6.6.5 Power factor 

The power factor of the machine shall be determined for each load point using Equation (59), See 5.1 1 . 

6.6.6 Summary of characteristics 

The summary of characteristics is a listing of the power factor, the efficiency, the speed and the line current 
at precise load points. To obtain this information, plot the values from the analysis for the line current, 
speed, and efficiency vs. the output power. Fit curves to these data and pick the values off for the desired 
load points. The power factor is computed for each precise load point from its amperes, volts, and input 
watts as in Equation (59). 

This summary of machine characteristics is included in Form C. See 9.8. 

6.7 Efficiency Test Method E or E1 -Electrical power measurement with loss 
segregation 

This test method measures the input power and determines the output power by subtracting the total losses 
from the input. The total losses are equal to the sum of stator and rotor losses corrected to the specified tem- 
perature for resistance correction, core loss, friction and windage loss, and stray-load loss. 

6.7.1 Test procedure 

6.7.1.1 Cold resistance 

With the machine at ambient temperature, measure and record the winding(s) resistances and the ambient 
temperature. 

6.7.1.2 Test under load 

To obtain the required data, it is necessary to couple, belt, or gear the machine to a variable load and test per 
5.6.2. 

6.7.1.3 No-load test 

Perform a no-load test in accordance with 5.5. 

6.7.1.4 Stray-load test 

The value of stray-load loss at full load for use with Efficiency Test Method E is determined by the direct 
method. Perform the test per 5.7.2 or 5.7.3. Efficiency Test Method El uses an assumed value from 5.7.4 
and no test is required. 

46 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

6.7.2 Calculations 

6.7.2.1 Calculation form 

Calculate motor or generator performance using Form E in 9.10 as a guide. The source of each of the items 
on Form E or the method of its calculation is shown on Form E2 in 9.1 1 . 

6.7.2.2 Windage and friction loss 

See 5.5.4. 

6.7.2.3 Core loss 
See 5.5.5. 

6.7.2.4 Stator t 2 R loss 

See 5.2. 

The stator I 2 R loss shall be corrected to the specified winding temperature. The stator winding resistance for 
each load point can be estimated by comparing the temperature rise measured by an embedded temperature 
detector, a temperature sensor located on the stator coil end, or the air outlet temperature rise, with corre- 
sponding temperature rise measurements obtained as steady -state values during a temperature test. When no 
temperature test is performed, the comparison is made with the total temperature assumed for the test. 

6.7.2.5 Rotor l 2 R loss 

See 5.3. 

The slip value shall be corrected to the specified winding temperature before performing this calculation. 

6.7.2.6 Stray-load loss 

With the full load stray-load loss established by the test in 6.7.1 .4, the loss level for each of the load points is 
determined by a ratio of the square of the rotor currents. See Equation (22). The rotor currents used at each 
of these points is calculated using Equation (23). 

6.7.2.7 Total losses and output power 

The total losses of the machine are the sum of the windage and friction losses, the core loss, the stator I"R 
loss, the rotor I"R loss, and the stray-load loss. 

The output power at the shaft for a motor is equal to the electrical input to the stator minus the above total 
losses. 

For a generator, the output power is equal to the electrical input power during the load test and the input 
power at the shaft is equal to the test electrical power input power plus the above losses. 

6.7.3 Motor/generator performance 

The efficiency for each test point is calculated using the input and output values of 6.7.2.7. The values of 
efficiency, line current, and speed may be plotted against load and values at specific load levels may be 
selected for the machine performance report. The power factor for each of these specific loads is calculated 
as in 5.11. 



Copyright © 2004 IEEE. Ail rights reserved. 47 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

6.8 Efficiency Test Method F or F1 —Equivalent circuit 

When tests under load are not made, operating characteristics are calculated based upon the equivalent cir- 
cuit shown in Figure 2. The machine parameters in the equivalent circuit are derived from test data recorded 
during a no-load test and an impedance test. Accurate prediction of machine characteristics in the normal 
operating range will depend primarily upon the closeness by which /?2 represents the actual rotor resistance 
to currents of low frequency and, secondarily, upon the closeness by which X2 represents the actual rotor 
leakage reactance to currents of low frequency. Therefore, the most careful procedure during testing to 
determine the rotor characteristics at low frequency is imperative. 

6.8.1 Test procedure 

6.8.1.1 Cold resistance 

With the machine at ambient temperature, measure and record the winding(s) resistances and the ambient 
temperature. 

6.8.1.2 No-load test 

Perform a no-load test in accordance with 5.5. Prior to making this test, the machine shall be operated at no- 
load until the input power has stabilized. See 5.5.1 . 

6.8.1.3 Impedance test 

See 5.9.1. 

6.8.1.4 Friction and windage loss 
See 5.5.4. 

6.8.1.5 Core loss 
See 5.5.5. 

6.8.1.6 Determine equivalent circuit 

Determine the value of all parameters of the equivalent circuit. See 5.9. 

6.8.1.7 Stray-load loss 

6.8.1.7.1 Test Method F 
See 5.7.2 or 5.73. 

6.8.1.7.2 Test Method F1 
See 5.7.4. 

6.8.2 Calculation form 

The calculations start with the assumptions of slip values for each calculation point and proceed through 
steps shown in Form F2, 9.13. After completion of the first series of calculations, the results shall be 
reviewed and new slip values selected that may more clearly represent the desired load points. Repeat the 
calculations to complete the summary of characteristics. Iterative calculations can be used to determine the 

48 Copyright © 2004 IEEE. AN rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

proper slip values. Forms F and F2 (see 9.12 and 9.13) are used for the performance calculations. The forms 
are arranged on the basis of Xi and Xo remaining constant throughout the range of operation of the machine. 
Should the curve of locked-rotor current vs. voltage depart from a straight line in the range of currents under 
consideration in the test per 5.9.1 , each column of calculations in 9.1 2 shall use values of reactance obtained 
from this curve for the value of /j calculated in the column. 

6.8.3 Calculation of maximum torque 

Maximum or breakdown torque in a motor can be approximated from the calculation procedure in 9.13 
using the slip value shown in Equation (75). 

s = R * (75) 



R] + {X X +X 2 f 



See Figure 2 for explanation of symbols. 

6.9 Efficiency Test Method C/F, E/F, or E1/F1 —Equivalent circuit calibrated with 
one load point 

When a test point under load at a stator temperature of t t is available, the equivalent circuit derived in 6.8 
can be calibrated by finding improved values for Ri and Xm- The following procedure is used after initial 
values for the equivalent circuits parameters in 9.14 have been determined: 

a) Use Forms F and F2 (see 9.12 and 9.13), but start with the second line with an assumed value of 
R2/S for the test load point and the value ofR\ based on stator winding temperature of t t . After reach- 
ing the calculation of stator power, check calculated value of input current and input power vs. mea- 
sured values of input current and input power. 

b) Adjust R2/S and Xm and iterate until the calculated value of input power and input current both agree 
with the measured value of input current and input power within 1%. Other circuit parameters 
should not be adjusted. (Input power is primarily a function of /?2/s.) 

c) Obtain R2 by multiplying the final assumed value of R2/S by the measured value of slip in per unit of 
synchronous speed. This procedure establishes the value of Ri (without temperature correction) to 
be used in calculating the load performance characteristics. 

d) Correct R\ and Rj to the specified temperature, t s , using Equation (3), and determine performance at 
desired load points following the format shown in 9.12. 

6.9.1 Stray-load loss 

6.9.1.1 Test Method C/F 

For Method C/F, the stray -load loss shall be determined as follows: 

a) For both the motoring and generating load points, determine the average value of stray-load loss, 
Psiawi following the procedure in 6.6.2.6. 

b) Determine the average value of rotor current for both the motoring and generating load points using 
Equation (73) for both calculations. The average of these two values is havg fo r use in 
Equation (76). 

c) The value of stray-load loss, P$l> for any load point is then calculated as shown in Equation (76). 
Copyright © 2004 IEEE. All rights reserved. 49 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

?SL = PsiaJr 1 -) 2 ( 76 ) 

where 

PsLavg is the average value of stray-load loss from step a), 

1 2 is the rotor current, in A, determined by solution of the equivalent circuit for the appropriate load 

point, 
ha\% i s tne average value of rotor current, in A, from step b). 

The value of stray -load loss, P 'si, reported in 9.13 should correspond to a value of havg equal to the average 
value of rotor current as determined from step b). 

6.9.1.2 Test Method E/F 

See 5.7.2 or 5.7.3. 

6.9.1.3 Test Method E1/F1 
See 5.7.4. 

6.9.2 Calculations form 

See 9.12 and 9.13. 



7. Other performance tests 

7.1 Rotor voltage 

On wound-rotor machines, the voltages shall be measured between all rotor terminals, with the rotor locked 
and its windings open -circuited and with rated voltage being applied to the stator. If any unbalance is 
detected, it is usual practice to take readings with several rotor positions to determine an average. 

7.2 Locked-rotor tests 

7.2.1 Current 

This test may be performed either to check for quality or to determine performance. When possible, readings 
shall be taken at rated voltage and frequency since the current is not directly proportional to the voltage 
because of changes in reactance caused by saturation of the leakage paths. When the test is made to check 
the quality of squirrel-cage machines, it is possible to omit the mechanical means of locking the rotor by 
applying single-phase power of rated voltage and frequency to any two of the machine line terminals of a 
three-phase machine. With a three-phase machine, the line current will be approximately 86% and the power 
input will be approximately 50% of the corresponding values obtained with polyphase power. The values so 
obtained may be compared with those measured on a duplicate unit that has been subjected to a complete 
test. 

7.2.2 Torque 

The locked-rotor torque is taken as the minimum torque developed at rest in all angular positions of the 
rotor. The torque may be measured with a scale or force transducer with a rope and pulley, or with a brake 



50 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 12-2004 

or beam or it may be measured directly using an in-line torque transducer. Wound-rotor motors are always 
subject to variations in locked-rotor torque, depending on the angular position of the rotor with respect to the 
stator. For squirrel-cage motors, it is usual practice to lock the rotor in any convenient position. If the 
locked-rotor torque is not measured directly as mentioned above, the approximate locked-rotor torque may 
be calculated as shown in Equation (77). 



where 

T is torque, in N-m, 

P s i is the input power to stator, in W, 

Psir is the stator P-R loss, in W, at the test current (see 5 .2), 

Ph is the core loss, in W, at test voltage (see 5.5.5), 

n s is the synchronous speed, in r/min, 

C\ is a reduction factor to account for nonfund amenta! losses, 

hi is 9.549 for torque in N-m. 

NOTE— C, can be any value between 0.9 and 1 .0. Unless there is past experience to guide the tester, a value of .91 is 
suggested. 

7.2.3 Power 

Readings of input power shall be taken simultaneously with those of voltage, current, and torque. 

7.3 Tests for speed-torque and speed-current curves 

7.3.1 Definitions 

7.3.1.1 Speed-torque characteristic 

The speed-torque characteristic is the relationship between torque and speed, embracing the range from zero 
to synchronous speed for a motor and from synchronous speed to pull-out speed for an induction generator. 
This relation, when expressed as a curve, will include maximum (breakdown), pull up or pull out, and 
locked-rotor torques. 

For wound-rotor motors, the torque and current shall be measured between synchronous speed and the speed 
at which maximum torque occurs. The slip rings shall be short-circuited for this test. 

7.3.1.2 Speed-current characteristic 

The speed-current characteristic is the relationship between current and speed. This curve is generally plot- 
ted on the same sheet as the speed- torque curve, using a common speed scale for both curves. 

7.3.2 Speed-torque and speed-current curves procedure 

Any one of the methods listed in 7.3.2.1 through 73.2.4 may be used to obtain data for a speed-torque curve. 
The selection of the method will depend upon the size and the speed-torque characteristics of the machine 
and the testing facilities. In all four methods, sufficient test points should be recorded to ensure that reliable 
curves, including irregularities, can be drawn in the regions of interest from the test data. It is important that 
the frequency of the power supply be maintained constant throughout the test. For wound-rotor motors, the 
slip rings shall be short-circuited for this test. 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

Method 1 and Method 4 require the maintenance of constant speed for each reading. Therefore, they cannot 
be used in regions where the torque of the machine increases with speed more rapidly than that of the load- 
ing device. From the results of the following tests, adjusted to the rated voltage, curves of torque and current 
should be plotted vs. speed. 

7.3.2.1 Method 1 — Measured output 

A dc generator that has had its losses previously determined is coupled or belted to the motor being tested. 
An ac power supply of rated frequency is connected to the motor terminals. The voltage should be as high as 
can be impressed upon the motor terminals without excessive heating, at least 50% of rated voltage, if possi- 
ble. The speed of the motor for each test point is controlled by varying the load on the generator. 

In this test, readings are taken at speeds between approximately 1/3 synchronous speed and the maximum 
speed obtainable. The speed should be constant when the readings are taken, so that acceleration or deceler- 
ation power does not affect the results. At each speed setting, readings of voltage, current, and speed are 
taken for the induction motor, and readings of armature voltage and current and field current are taken for 
the dc generator. Care should be taken not to overheat the motor. 

The accuracy of speed measurement is particularly important at low slip. All points should be read as soon 
as the meters have settled, without waiting for the slow creep in the indications to disappear. 

The total power output of the motor is the sum of the power output and losses of the dc generator. 

The torque, 7\ at each speed is calculated as shown in Equation (78). 

n 

where 

T is torque, in N-m, 

Pqo is the generator output, in W, 

Pql is the losses of the generator (including friction and windage), in W, 

n is the test speed of motor, in r/min, 

hi is 9.549 for torque in N*m. 

At the speed for the test point, the values of torque and current are corrected to the specified voltage, V, as 
described in 73.3. 

7.3.2.2 Method 2— Acceleration 

In the acceleration method, the motor is started with no load, and the value of acceleration Is determined at 
various speeds. The torque at each speed is determined from the acceleration of the mass of the rotating 
parts. Accurate measurements of speed and acceleration are an essential requirement of this method. 

The acceleration to be used and the duration of the test are determined by the type of instruments that are 
used to make the measurements. In any case, the accelerating time should be long enough so that electrical 
transient effects in the instruments and in the motor do not distort the speed- torque curve. The accelerating 
time must also be long enough to permit recording the necessary number of mechanical and electrical mea- 
surements with sufficient accuracy for plotting the required curves (see 73.2). 

To provide sufficient time for recording the data at each point, the accelerating time may be increased by 
using a lower applied voltage or by coupling a suitable inertia to the motor shaft. 



52 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 112-2004 

As the motor accelerates from rest to near synchronous speed, simultaneous readings are taken of line-to- 
line voltage for one phase, line current in one phase, speed, and time in seconds. A minimum of five sets of 
readings should be taken during the accelerating period; however, more readings should be taken if possible. 
If the motor's starting friction is high, or if more accurate data in the zero speed range are desired, the motor 
can be started rotating in the reverse direction prior to application of power for the acceleration on which 
measurements are to be taken. 

If Method 3 (see 7.3.2.3) is to be used as a check, line power should be taken with a polyphase wattmeter or 
two single-phase wattmeters at each speed point where data are recorded. 

It may sometimes be necessary to take more than one run at different voltages in order to get satisfactory 
readings throughout the curve, especially when there are appreciable cusps in the speed -torque 
characteristics. 

The torque, 7\ at each speed is calculated from the acceleration using Equation (79). 
rr J dn 



k 2 dt 



where 

T is torque, in N*m, 

./ is the moment of inertia of rotating parts, in kg * m 2 , 



(79) 



is the acceleration at each speed, in revolutions per minute per second, 



dn 
It 
ki is 9.549 for torque in N-m 



At the speed for the test point, the values of torque and current are corrected to the specified voltage, V, as 
described in 7.3.3. 

7.3.2.3 Method 3-lnput 

In this method, the torque is determined by subtracting the losses in the machine from the input power. It is 
a valuable check on the other methods, and is particularly useful when the machine cannot be unloaded to 
determine torque by acceleration. In practice, the method is approximate because the stator losses cannot be 
readily determined for the actual operating conditions and, therefore, must be approximated. This method is 
also subject to error in the case of special machines that may have substantial positive or negative harmonic 
torques that are not readily evaluated. 

The machine is started as described in 7.3.2.2, except that it does not have to be unloaded. The input read- 
ings called for in 7.3.2.2 are plotted against the speed readings. The line voltage, line current, power, and 
speed should be plotted vs. time. Average values of the zero speed readings from the locked test, as 
described in 7.2.2, adjusted to the voltage at which the other readings were taken, should be included. 

The torque, 7, at each speed is determined from the input power using Equation (80). 

T fv (80) 



r 


"*2~ 
-'V 














r.{ 


X 


Psi ~ Psir ~ 


-p„- 


-P S L, 


-P S Lr>< i 


in 

V fl s 


where 












T 


is to 


rqu 


e, in N*m, 











Copyright © 2004 IEEE. All rights reserved. 53 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

P s i is the input power to stator, in W , 

Psir is the stator/ 2 /? loss, in W, at the test current (see 5.2), 

Pit is the core loss, in W, at the test voltage (see 5.5.5), 

P$Ls *$ the fundamental frequency stray-load loss, in W, at the test current (see 5.7.2.1), 

Psu is the higher frequencies stray-load loss, in W, at the test current (see 5.7.2.2), 

n is test speed, in r/min, 

n s is the synchronous speed, in r/min, 

k-2 is 9.549 tor torque in N*m, 

Tf w is the motor friction and windage torque at test speed, in N-m. 

NOTE— If the Psu component of stray load loss is not available, it may be assumed that the stray load loss is equal to 
Psu- If the stray load loss {Psu + PsLr ) na s been determined from a dynamometer test, the total value of stray-load loss 
may be used as the value of Psu; or, the value of Psu ma y he determined by the method outlined in 5.7.2.1 , and Psu 
may be determined as the value of stray load loss minus the value of Psu • 

At the speed for the test point, the values of torque and current are corrected to the specified voltage, V, as 
described in 7.3.3. 

7.3.2.4 Method 4— Direct measurement 

The torque and current are measured as the machine is loaded at various speeds with a dynamometer or 
mechanical brake. At each speed, simultaneous readings of voltage, current, speed, and torque are taken. 
The test should be taken as near rated voltage as practical. If a reduced voltage is used, the values of torque 
and current should be corrected to the specified voltage as described in 7.3.3. 

7.3.3 Correction of data for tests performed at reduced voltage 

When it is necessary to establish values of current and torque at rated voltage, based on speed-torque, speed- 
current, and locked-rotor tests made at reduced voltage, it should be recognized that, because of saturation of 
the leakage flux paths, the current may increase by a ratio somewhat greater than the first power of the 
voltage; and the torque may increase by a ratio somewhat greater than the square of the voltage. The rela- 
tionship varies with design; however, as a first approximation, the current is calculated as varying directly 
with voltage, and torque with the square of voltage. 

A more exact method of test requires determining the rate of change of current and torque with voltage by 
establishing speed- torque and speed-current curves for at least two, and preferably for three or more, values 
of voltage. The reduced- voltage test points should be plotted on log- log paper and corrected to rated voltage 
using a least square curve fit for maximum accuracy. On speed- torque and speed-current curves, enough 
points at various speeds must be corrected to provide true representation of the curve over the entire speed 
range. 



8. Miscellaneous tests 



8.1 Insulation resistance 

For maintenance purposes, insulation resistance tests are of value. All accessories, such as surge capacitors, 
surge arresters, current transformers, etc., that have leads located at the machine terminals shall be discon- 
nected during this test, with the leads connected together and to the frame or core. 

For test methods, see IEEE Std 43-2000. 



54 Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

8.2 High-potential test 

8.2.1 General 

High-potential tests are tests that consist of the application of a voltage higher than the rated voltage for a 
specified time for the purpose of determining the adequacy against breakdown of insulating materials and 
spacings under normal conditions. 

The test voltage should be applied when, and only when, the machine is in good condition and the insulation 
resistance is not impaired due to dirt, moisture, or abrasion or other types of damage. See IEEE Std 43-2000. 

8.2.2 Measurement 

For measurement of high-potential test voltage, see IEEE Std 4-1995 [B6]. The voltmeter method of mea- 
surement is commonly used. 

8.2.3 Connections 

The high-potential test voltage shall be successively applied between each electric circuit and the frame, 
with the windings not under test and the other metal parts connected to the frame. Interconnected polyphase 
windings are considered as one circuit. All accessories such as surge arresters, current transformers, etc., 
that have leads located at the machine terminals shall be disconnected during this test, with the leads 
connected together and to the frame or core. No leads shall be left unconnected during the test as this may 
cause an extremely severe stress at some point of the winding. 

8.2.4 Test voltage 

The commonly specified high-potential test voltage for factory testing of new stators is 1000 volts plus 2 
times the rated voltage of the machine. Likewise for new rotors of wound rotor machines the test voltage is 
1000 volts plus 2 times the maximum voltage induced between collector rings. Refer to NEMA MG 1- 2003 
[B7] Part 12 and Part 20 to confirm the voltage level for the specific machine under test. 

Since high-potential testing is stressful on winding dielectric components, it is recommended that initial 
field high-potential test voltages be limited to 85% of the levels used for factory testing of new equipment. 
For any further high potential testing, it is recommended the test voltage level be limited to a 75% level. 

8.2.5 Voltage application 

In performing the test, the voltage shall be increased to full value as rapidly as possible while still maintain- 
ing an accurate meter reading, and the full voltage should be maintained for 1 min. It should then be reduced 
at a rate that will bring it to 1/4 value or less in not more than 1 5 seconds. 

To avoid excessive stressing of the insulation components, repeated application of the high-potential test 
voltage is not recommended. 



WARNING 
Due to the high voltage used, high-potential tests should be conducted only by experienced personnel, and ade- 
quate safety precautions should be taken to avoid injury to personnel and damage to property. For the procedures 
recommended , refer to IEEE Std 4- 1 995 [B6] . 



Copyright © 2004 IEEE. All rights reserved. 55 



IEEE 

Std 1 12-2004 IEEE STANDARD TEST PROCEDURE FOR 

8.3 Shaft current and voltage 

Shaft currents can flow in rotating machinery as a consequence of electromagnetically developed voltages in 
the shaft or frame. 

In electrical machines, any unbalance in the magnetic circuits, or in the electrical phase currents that encircle 
a shaft, can create flux linkages with the rotating system. When the shaft rotates, these linkages can produce 
an electric potential difference between shaft ends. This voltage is capable of driving a circulating current in 
a shaft- to- frame loop by using two bearings to complete the circuit. 

If the opposite drive end bearing (or both bearings) is/are isolated from the frame, the conducting path is 
impeded by the insulation, and the circulating shaft current in that machine is inhibited. If only the drive end 
bearing is insulated, however, the current may be able to circulate by using the opposite end bearing in con- 
junction with an uninsulated bearing in the interconnected equipment to complete the circuit. 

8.3.1 Test to measure shaft potential for circulating shaft currents 

In machines that have insulation on all bearings (or all but one bearing), a test can be conducted to detect the 
presence of shaft potential while the unit is operating. This test can also be applied to machines that have 
insulating properties in all bearing oil films. 

The test is completed by measuring the shaft potential to the frame at each of the other bearings. A high 
impedance oscilloscope should be utilized and connected with one lead grounded to the frame and the other 
lead attached to a shaft brush. This brush is then applied to a shaft section near each bearing and the peak 
voltages are measured. First, a shaft brush is used to short out the uninsulated bearing (or one bearing, if all 
are insulated). This fixed brush is applied to the shaft near the bearing and connected to the frame with a 
short piece of low-resistance conductor. 

It is preferable to use a low-impedance shielded conductor for the oscilloscope leads to minimize electro- 
magnetic interference. This shield should be grounded at one end only. 

If an oscilloscope is not available for the test, a high-impedance voltmeter can be used. Both ac and dc volt- 
ages should be measured at each bearing. The peak voltage can be roughly approximated by adding the dc 
level and 1.4 times the ac rms level. This estimated peak voltage, however, may be considerably below the 
actual peak value. 

An alternate method involves measuring the ac voltage with brushes contacting opposite ends of the shaft 
while the machine is operating at rated voltage and speed. 

8.3.2 Test to measure possible level of shaft current 

This test can be conducted on machines as described in 8.3,1 . The procedure is identical to that of 8.3,1 , with 
the exception that a low-resistance ammeter is used in place of the oscilloscope. 

NOTE— In this test arrangement, the ammeter is being used as a low-impedance, uncalibrated voltmeter. The meter 
readings may not be a true indication of the current that might How should there be a breakdown of the lubrication film 
in the bearing(s). This method may be useful if a history of results from similar tests is available. 

8.3.3 Other methods 

If special means for measurement of shaft currents, such as Rogowski loops, are a feature of the machine 
under test, these may be used in lieu of or to supplement the above test methods. 



56 Copyright © 2004 IEEE. AN rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

8.4 Bearing insulation resistance 

8.4.1 Method 1 

The most reliable check on bearing insulation is performed with the unit at rest. If only one bearing is insu- 
lated, a layer of insulating paper should be applied under the uninsulated bearing journal to insulate the shaft 
from the bearing. Couplings to adjacent units should be disengaged if they are not insulated. 

A low-voltage ohmmeter should be used to make a preliminary check at each insulated bearing. With one 
ohmmeter lead applied to the shaft and the other to the frame (across the insulation), the bearing insulation 
resistance can be measured. 

On machines with two layers of bearing insulation and with a metallic separator between layers, this test 
should be performed between the metallic separator and the machine frame. The test can be conducted while 
the machine is running, but it is preferable to conduct the test with the machine at rest. The test should be 
supplemented with a careful visual inspection to ensure that there are no possible parallel paths that are 
uninsulated. 

8.4.2 Method 2 

A layer of heavy paper is placed around the shaft to insulate the journals of the uninsulated bearings. The 
coupling of the driving or driven units should be disengaged, if it is not insulated. Then, from a 1 10-1 25 V 
source with either a filament lamp suitable for the circuit voltage or a voltmeter of approximately 150 V full 
scale with a resistance in the range of 100-300 Q/V placed in series with the voltage source, two leads 
should be run, one to the insulated bearing and the other to the frame (across the insulation). If the lamp fil- 
ament does not show color (or if the reading of the, voltmeter does not exceed 60 V), the insulation may be 
considered satisfactory. 

A 500 V megohmmeter may also be used. This is much more sensitive than the above method and may tend 
to reject insulation, which, in reality, is adequate to prevent the small shaft voltage from causing injurious 
current. See 8.4.1. 

8.5 Noise 

For noise (sound level) tests refer to NEMA MG 1-2003 [B7] Part 9 and IEC 60034-9 [B3J. 

8.6 Balance and vibration 

8.6.1 Rotor balance 

Motor and generator rotors should be dynamically balanced with a half key in place. 

8.6.2 Vibration 

For vibration tests, refer to NEMA MG 1-2003 [B7] Part 7, IEC 60034-14 [B4] or API Std 541 , 4th Edition 
[B2]. 

8.7 Overspeed 

When overspeed tests are performed, precautions shall be taken to protect personnel and equipment. 
Copyright © 2004 IEEE. All rights reserved. 51 



IEEE 

Std 112-2004 IEEE STANDARD TEST PROCEDURE FOR 

9. Forms 

9.1 Test forms and support information 

This test procedure does not require that the test forms presented must be used, however, the forms and 
supporting information do show the sequence of tests that must be used and do guide the calculations with 
equations using the line item numbers from the forms. It is expected that the test analyses will be accom- 
plished using computer programs and in many cases with data being obtained by electronic means and going 
directly into the analysis program. 

9.1.1 Summary of characteristics 

A table or listing of the summary of characteristics is a part of each test form. With most of the test methods, 
the values at specific load values are obtained from plots of the calculated values of the test points. From a 
curve defined by these points, the values for the points of interest may be obtained. Load values of 25, 50, 
75, 100, 125, and 150 percent of rated load are commonly used. Any other load of interest can also be 
shown. The power factor here is calculated for each precise load point using the voltage, current, and power 
obtained from the plotted data. The data plots mentioned may be a manual or a computer generated plot or 
the required data values at the specific load points may be calculated from a computerized virtual curve if 
such programs are available. Data summaries for Method F testing may be calculated for the precise desired 
points; a plot of the data is not necessary. 



58 Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



9.2 Form A-Method A 



Type 

Frequency,. 



_ Design _ 



. Frame _ 



_Rating . 



_ Volts . 



Degrees C Temperature Rise _ 



_ Synchronous r/min . 
Time Rating 



Phase „ 

_Serial No. 

/Model No. _ 



Specified temperature. f v , in °C 


Synchronous speed.n. in r/min 


Stator Resistance. Terminal-to-Terminal 

Ohms @ °C 


Test Point (Motoring) (Generating) 


1 


2 


3 


4 


5 


6 


Stator Winding Temperature, tt, in "C 














Ambient Temperature, in °C 














Line-to-Line Voltage, in V 














Frequency, in Hz 














Observed Speed, in r/min 














Observed Slip, in r/min 














Observed Slip, in p.u. 














Corrected Slip, in p.u. 














Corrected Speed, in r/min 














Torque, in N-m 














Dynamometer Correction, in N-m 














Corrected Torque, in N-m 














Shaft Power, in W 














Line Current, in A 














Stator Power, in W 














(a) Stator l 2 R Loss, in W, at /, 














(b) Stator f 2 R Loss, in W, at is 














Stator Power Correction = (b) - (a) 














Corrected Stator Power, in W 














Efficiency, in % 














Power Factor, in % 















Performance Curve 



Summary of Characteristics 



Load, in % of rated 


25 


50 


75 


100 


125 


150 


Power Factor, in % 














Efficiency, in % 














Speed, in r/min 














Line Current, in A 















Copyright © 2004 IEEE. All rights reserved. 



59 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



9.3 Form A2-Method A calculations 



'type 

Frequency _ 



Design 



-.Volts . 



Degrees C Temperature Rise _ 



. Frame _ 



.Synchronous r/min _ 
Time Rating . 



JRating , 



Phase „ 

„Serial No. 
Model No. „ 



Specified temperature, / iV , (1 ) , in °C. 

See 3.3.2. 


Synchronous speed. n s , 
(2) , in r/min 


Stator Resistance. Terminal -to-Terminal 
(3) Ohms @ (4) °C See6.3.1 .1 


Item 


Test Point (Motoring)(Generating) 


Source or Calculation 


1 


2 


-- 


6 


5 


Stator Winding Temp, tt in °C 


From each test point. From 6.3.1 .3 










6 


Ambient Temperature, in °C 


From each test point. From 6.3.1 .3 










7 


Line-to-Line Voltage, in V 


From each test point. From 6.3.1 .3 










8 


Frequency, in Hz 


From each test point. From 6.3.1 .3 










9 


Observed Speed, in r/min 


#(9) = (2) -(10) 










10 


Observed Slip, in r/min 


#(10) = (2) -(9) 










n 


Observed Slip, in p.u. 


(11) = (10)/ (2) 










12 


Corrected Slip, in p.u. 


See 5.3.2 










13 


Corrected Speed, in r/min 


(13) = (2)x[l-(12)] 










14 


Torque, in N-rn 


From each test point. From 6.3.1 .3 










15 


Dynamometer Correction, in N-m 


From calculation per 5.6.1.2 










16 


Corrected Torque, in N-m 


For motoring: (16) = (14) + (15) 
For generating: (16) = (14) - (15) 










17 


Shaft Power, in W 


(17) = (16) x (13)/ 9.549 










18 


Line Current, in A 


From each test point. From 6.3.1 .3 










19 


Stator Power, in W 


From each test point. From 6.3.1 .3 










20 


Stator l 2 R Loss, in W, at tt 


*(20) = 1 .5 x (18) 2 x (3) x (LA, + (5)]/L*] + (4) J} 










21 


Winding Resistance at t s 


Correct (3) using Equation (3) 










22 


Stator I 2 R Loss, in W, at r s 


(22)= 1.5x(l8) 2 x(21) 










23 


Stator Power Correction 


(23) = (22) -(20) 










24 


Corrected Stator Power, in W 


For motoring: (24) = (19) + (23) 
For generating: (24) = (19) - (23) 










25 


Efficiency, in % 


For motoring: (25) = 100 (1 7)/(24) 
For generating: (25) = 100 (24)/(17) 










26 


Power Factor, in % 


(26) = 100 x (24) / [1 .732 x (7) x (18) J 











# Enter the measured speed or measured slip for each test point on the proper line and use formulas provided to calculate the other 
parameter. 

* In (20) select/:] based on the stator conductor material. See 5.2.1. 
Parentheses, (), normally used with equation numbers are not used here to avoid confusion with the form item numbers. 



60 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



9.4 Form B-Method B 



Type 

Frequency. 



_Desisn_ 



Volts 



Degrees C Temperature Rise . 



. Frame _ 



.Synchronous r/min __ 
Time Rating _ 



„Rating 



Phase.. 

_Serial No. „ 

Model No. _ 



Cold St a tor Winding Resistance Between Terminals Ohms @ °C 


Rated Load Temp. Test Stator Winding Resistance Between Terminals Ohms @ °C in °C Ambient 

Rated Load Temperature Test Stator Temperature Rise °C 
Total Stator Temperature. /, °C in a 25 °C Ambient 


Description (Motoring)(Generating) 


1 


2 


3 


4 


5 


6 


Ambient Temperature, in °C 














Stator Winding Temperature. t v in °C 














Frequency, in Hz 














Synchronous Speed, in r/min 














Speed, in r/min 














Slip Speed, in r/min 














Slip in p.u. 














Line-to-Line Voltage, in V 














Line Current, in A 














Stator Power, in W 














Core Loss, in W 














Stator/ 2 /? Loss, in W, at/, 














Power Across Air Gap, in W 














Rotor/ 2 /? Loss, in W 














Friction and Windage Loss, in W 














Total Conventional Loss, in W 














Torque, in N-m 














Dynamometer Correction, in N-m 














Corrected Torque, in N-m 














Shaft Power, in W 














Apparent Total Loss, in W 














Stray -Load Loss, in W 














Intercept Slope Correlation Fa 


ctor 


J oint Deleted 








Stator I 2 R Loss, in W, at t x 














Corrected Power Across Air Gap, in W 














Corrected Slip, in p.u. 














Corrected Speed, in r/min 














Rotor f 2 R Loss, in W, at h 














Connected Stray-Load Loss, in W 














Corrected Total Loss, in W 














Corrected Shaft Power, in W 














Efficiency, in % 














Power Factor, in % 















The Summary of Characteristics shall be presented as with Form A in 9.2. For additional guidance, see 9.1.1 . 



Copyright © 2004 IEEE. All rights reserved. 



61 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



9.5 Form B2-Method B calculations 



Cold Stator Winding Resistance Between Terminals (! ) Ohms @ __ __(2) °C From 6.4. U 


Hoi Stator Winding Resistance Between Terminals (3) Ohms @ _(4) °C in (5) D C Ambient From 6.4.1.2 


Raied Load Temp. Test Stator Temperature Rise (6) °C, (6) = (4) - (5) 


(4)={[(3)/(1)]xl* ] +(2)1}~* ] 


Total Stator Temperature, t s , (7) °C in a 25 °C Ambient, (7) = (6) + 25 


If (6) & (7) are from duplicate, (3), (4) & (5) are N/A 


Item 


Description (Motoring)(Gene rating) 


Source or Calculation 




8 


Ambient Temperature, in °C 


From each test point, from 6.4.1 .3 




9 


Stator Winding Temperature, t h in °C 


From each point, adjusted per 6.4.2,4 




JO 


Frequency, in Hz 


From each test point, from 6.4.1.3 




n 


Synchronous Speed, in r/min 


=1 20 x (10) / number of poles 




12 


Speed . in r/min 


*=(n)-03) 




13 


Slip Speed, in r/min 


*=(11)-(12) 




14 


Slip in p.u. 


= (13)/ (11) 




15 


Line- to- Line Voltage, in V 


From each test point, from 6.4.1 .3 




16 


Line Current, in A 


From each test point, from 6.4.1 .3 




17 


Stator Power, in W 


From each test point, from 6.4.1 .3 




18 


Core Loss, in W 


From 5.5.5 at voltage equal to (15) 




19 


Stator f 2 R Loss, in W, 


= 1 .5 x (16) 2 x R , Adjust R see 6.4.2.4 




20 


Power Across Air Gap, in W 


= (17)-(18)-(19) for motor 
= (17) + (18) + (19) for generator 




21 


Rotor I 2 R Loss, in W 


= (20)x(14) 




22 


Friction and Windage Loss, in W 


From 5.5.4 




23 


Total Conventional Loss, in W 


= (18) + (19) + (21) + (22) 




24 


Torque, in N-m 


From each test point, from 6.4.1 .3 




25 


Dynamometer Correction, in N-m 


From test per 5.6.1 .2, if needed 




26 


Corrected Torque, in N-m 


= (24) + (25) 




27 


Shaft Power, in W 


= (26) x (12)/ 9.549 




28 


Apparent Total Loss, in W 


= (.17) -(27) for a motor 

= (27) - (17) for a generator 




29 


Stray-Load Loss, in W 


= (28) »(23) 




Intercept (30) Slope (31) Correl 


3tion Factor (321 


. Point Deleted (33) 


(30), (31 ), (32) & (33) from the linear regression ana 


lysis of (29) & (26) entries as described in 6.4.2.8 


34 


Stator I 2 R Loss, in W, at t s 


= 1.5x(l6) 2 x(3)x{LA ]+ (7)J/LAj + (4)J} 




35 


Corrected Power Across Air Gap, in W 


= (17) -(18) -(34) 




36 


Corrected Slip, in p.u. 


= (14) x LA' , + (7)]/^ +(9)j 




37 


Corrected Speed, in r/min 


= (1.1) x [1.00 -(36)] 




38 


Rotor I 2 R Loss, in W, at t s 


= (36) x (35) 




39 


Corrected Stray-Load Loss, in W 


= (31)x(26) 2 




40 


Corrected Total Loss, in W 


= (18) + (22) + (34) +(38) + (39) 




41 


Conected Shaft Power, in W 


= (1.7) -(40) 




42 


Efficiency, in % 


= 100(40/(17) for a motor 
= 100(17)/(41) for a generator 




43 


Power Factor, in % 


= 100 x (17)/ [1.732 x (15) x (16)] 





* Enter the measured speed or measured slip speed for each test point on the proper line and use the formula provided to calculate the 
other parameter. In (4), (19), (34), and (36), select k] based on conductor material. See 5.2.1 and 5.3.2. See 9.1.1 for Summary of 
Characteristics. 



62 



Copyright © 2004 IEEE. AN rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



9.6 Form B1~Method B1 



Type 

Frequency. 



_Design_ 



_ Volts . 



Degrees C Temperature Rise _ 



_ Frame _ 



_ Synchronous r/min _ 
Time Rating, 



_Ralirm . 



.Phase. 



.Serial No. . 
_Model No.. 



Cold Stator Winding Resistance Between Terminals Ohms @ C C 


S pec i fi ed S t ator Te m pe ra tu re . / „ ° C i n a 25 ° C A mbi en t 


Description (Motoring)(Generating) 


1 


2 


3 


4 


5 


6 


Ambient Temperature, in °C 














Stator Winding Temp, (Y r ), in °C 














Frequency, in Hz 














Synchronous Speed, in r/min 














Speed, in r/min 














Slip Speed, in r/min 














Slip in p.u. 














Line-to-Line Voltage, in V 














Line Current, in A 














Stator Power, in W 














Core Loss , in W 














Stator I 2 R Loss, in W, at/; 














Power Across Air Gap, in W 














Rotor/ 2 /? Loss, in W 














Fri c ti on a nd Wi n da ge Lo s s , i n W 














Total Conventional Loss, in W 














Torque, in N-m 














Dynamometer Correction, in N-m 














Co rrec ted To rq u e , i n N - m 














Shaft Power, in W 














Apparent Total Loss, in W 














Stray-Load Loss, in W 














Intercept Slope Correlation Factor Point Dek 


•led 




Stator/ 2 /? Loss, in W, at t s 














Conected Power Across Air Gap, in W 














Corrected Slip, in p.u. 














Corrected Speed, in r/min 














Rotor I 2 R Loss, in W> at t s 














Corrected Stray- Load Loss, in W 














Corrected Total Loss, in W 














Corrected Shaft Power, in W 














Efficiency, in % 














Power Factor, in % 















The Summary of Characteristics shall be presented as with Form A in 9.2. For additional guidance, see 9.1 .1 . 



Copyright © 2004 IEEE. All rights reserved. 



63 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



9.7 Form B1-2-Method B1 calculations 



Cold Stator Winding Resistance Between Terminals (1) Ohms @ (2) °C From 6.5.1.1 


Specified Stator Temperature, (t s ), (3) °C in a 25 °C Ambient, From 3.3.2 c) 


Item 


Description (Motoring)(Generating) 


Source or Calculation 




4 


Ambient Temperature, in "C 


From each test point, from 6.5.1 .4 




5 


Stator Winding Temp, t t , in °C 


From each test point, from 6.5.1 .4 




6 


Frequency, in Hz 


From each test point, from 6.5.1 .4 




7 


Synchronous Speed, in r/min 


= 120 x (6) / number of poles 




8 


Speed, in r/min 


*= (7) ™ (9) 




9 


Slip Speed, in r/min 


*= (7) - (8) 




10 


Slip in p.u. 


= (9)/ (7) 




11 


Line-to-Line Voltage, in V 


From each test point, from 6.5.1 .4 




12 


Line Current, in A 


From each test point, from 6.5.1 .4 




13 


Stator Power, in W 


From each test point, from 6.5.1 .4 




14 


Core Loss, in W 


From 5.3.5 at voltage equal to (1 1) 




15 


Stator I 2 R Loss, in W, at t t 


= J.5x(12) 2 x(])x{|A J +(5)l/|A ] + (2)]} 




\6 


Power Across Air Gap, in W 


-(13)-(14)-(15)foramolor 
= (13) + (14) + (15) for a generator 




17 


Rotor./ 2 /? Loss, in W 


= (16)x(10) 




38 


Friction and Windage Loss, in W 


From 5.5.4 




19 


Total Conventional Loss, in W 


= (14) + (15) + (17) + (18) 




20 


Torque, in N-m 


From each test point, from 6.5.1 .4 




21 


Dynamometer Correction, in N-m 


From test per 5.6.1 .2, if needed 




22 


Corrected Torque, in N-m 


= (20) + (21) 




23 


Shaft Power, in W 


= (22) x (8)/ 9.549 




24 


Apparent Total Loss, in W 


= (13) -(23) for a motor 

= (23) - (1 3) for a generator 




25 


Stray-Load Loss, in W 


-(24) -(19) 




Intercept (26) Slope (27) Correlation Factor (28) Point Deleted (29) 

(26), (27), (28) & (29) from the linear regression analysis of (25) & (22) entries as described in 6.4.2.7 


30 


Stator J 2 R Loss, in W, at t s 


= 1.5x(16) 2 x0)x{L*i+(3)]/[*]+(2)J} 




31 


Corrected Power Across Air Gap. in W 


= (13) -(14) -(30) 




32 


Corrected Slip, in p.u. 


= (10)x[* J +(3)]/[A 1 + (5)] 




33 


Corrected Speed, in r/min 


= (7) x [1.00 -(32)] 




34 


Rotor l 2 R Loss, in W, at t s 


= (31)x(32) 




35 


Corrected Stray-Load Loss, in W 


= (27) x (22) 2 




36 


Corrected Total Loss, in W 


= (14) + (18) + (30) +(34) + (35) 




37 


Corrected Shaft Power, in W 


= (13) -(36) 




38 


Efficiency, in % 


=.100(37)/(13)faramotor 
= 100(13)/(37) for a generator 




39 


Power Factor, in % 


= 100 x (13)/ [1.732 x (11) x (12).] 





* Enter the measured speed or measured slip speed for each test point on the proper line and use the formula provided to calculate the 
other parameter. In (15), (30), and (32), select k] based on conductor material. See 5.2.1 and 5.3.2. See 9.1.1 for Summary of 
Characteristics. 



64 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



9.8 Form C-Method C 



Type 

Frequency„ 



JDesign _ 



.Volts . 



Degrees C Temperature Rise . 



_ Frame _ 



_ Speed r/min_ 



. Time Rating, 



Jip/kW . 



Phase _ 

_Serial No. _ 
Model No._ 



Ml 


Vra^ <^ld ^\-A<* Windina Resistance. Ret ween Terminals Ohms @ °C 


M2 


Average r old Stator Winding Resistance Retween Terminals Ohms @ °C 


Total Specified Stator Temperature, t, °C in a 25 °C Ambient 


Test Point > 


1 


2 


3 


4 


5 


6 


Description 


Ml 


M2 


M 1 


M2 


M 1 


M2 


M 1 


M2 


M 1 


M2 


M 1 


M2 


Part A of Test Point - Machine 1 as a motor and Machine 2 as a generator 


Ambient Temperature, in °C 


























Stator Winding Temp, f,, in °C 


























Frequency, in Hz 


























Synchronous Speed, in r/min 


























Speed, in r/min 


























Slip Speed, in r/min 


























Slip, in p.u. 


























Line-to-Line Voltage, in V 


























Volts / Hertz 


























Line Current, in A 


























Stator Power, in W 


























Core Loss, in W 


























Stator 1 2 R Loss, in W, at i t 


























Power Across the Air Gap, in W 


























Rotor I 2 R Loss, in W 


























Friction and Windage Loss, in W 


























Total Conventional Loss, in W 


























Rotor Current, in A 


























Combined Stray-Load Loss, in W 














Stray -Load Loss, in W 






1 


















Part B of Test Point- Machine 1 as a generator and Machine 2 as a motor 


Ambient Temperature, in °C 


























Stator Winding Temp, t T , in °C 


























Frequency, in Hz 


























Synchronous Speed, in r/min 


























Speed, in r/min 


























Slip Speed, in r/min 


























Slip, in p.u. 


























Line-to-Line Voltage, in V 


























Volts / Hertz 


























Line Current, in A 


























Stator Power, in W 


























Core Loss, in W 


























Stator l 2 R Loss, in W, at /, 



























Form C, Part 1 



Copyright © 2004 IEEE. Alf rights reserved. 



65 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



Test Point > 


1 


2 


3 


4 


5 


6 


Description 


M 1 


M2 


Ml 


M2 


Ml 


M2 


Ml 


M2 


M i 


M2 


M 1 


M2 


Power Across the Air Gap, in W 


























Rotor/ 2 /? Loss, in W 


























Friction and Windage Loss, in W 


























Total Conventional Loss, in W 


























Rotor Current, in A 


























Combined Stray-Load Loss, in W 














Stray-Load Loss, in W 






























Machine 1 


Machine 2 




] 


2 


3 


4 


5 


6 


1 


2 


3 


4 


5 


6 


Average Rotor Current, in A 


























Average Stray-Load Loss, in W 




















































Linear Regression Analysis 


Machine I. - intercept Slope Correlation Factor 












Machine 2 - Intercept Slope Con-elation Factoi 












Corrected Values 


Stator7 2 tf Loss,in W, at ^ 


























Power Across Air Gap, in W 


























Slip, in p.u. 


























Speed, in r/min 


























Rotor I 2 R Loss, in W, at /\, 


























Stray -Load Loss, in W 


























Total Loss, in W 


























Shaft Power, in W 


























Efficiency, in % 



























Summary of Characteristics 
Machine 1 



Load, in % of rated 


25 


50 


75 


100 


125 


150 


Power Factor, in % 














Efficiency, in % 














Speed, in r/min 














Line Current, in A 














Summary of Characteristics 
Machine 2 


Load, in % of rated 


25 


50 


75 


100 


125 


150 


Power Factor, in % 














Efficiency, in % 














Speed, in r/min 














Line Current, in A 















Form C, Part 2 



66 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



9.9 Form C2~Method C Calculations 



Type . 



Frequency. 



.Design „ 



_ Frame _ 



Volts . 



_Speed r/m.in_ 



„hp/kW . 



„Phase„ 



Degrees C Temperature Rise . 



Time Ratine _ 



„Serial No. . 

Model No.. 



Ml 


Average Cold Stator Winding Resistance Between Terminals ____(1) Ohms @ (2) °C 


M2 


Average Cold Stator Winding Resistance Between Terminals (3) Ohms @ _(4) D C 


Total Specified Stator Temperature, t s (5) °C in a 25 °C Ambient I 


Item 


Test Point> 


l,Etc. 


Ml 


M2 


Description 


Machine 1 


Machine 2 


Part A of Test Point - Machine 1 as a motor and Machine 2 as a generator 


6 


26 


Ambient Temperature, in "C 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


7 


27 


Stator Winding Temp, t t , in °C 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


8 


28 


Frequency, in Hz 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


9 


29 


Synchronous Speed, in r/min 


(9)= 1 20 x (8) /No. of poles 


(29)= 120 x (28) /No. of poles 


10 


30 


Speed, in r/min 


From each test point, from 6.6.1.3 


From each lest point, from 6.6.1 .3 


11 


31 


Slip Speed, in r/min 


From 6.6.1.3 or =(9) -(10) 


From 6.6.1.3 or =(30) -(29) 


12 


32 


Slip, in p.u. 


(12) = (ll)/(9) 


(32) = (31)/ (29) 


13 


33 


Line-to-Line Voltage, in V 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


14 


34 


Volts / Hertz 


(14) = (13)/ (8) 


(34) = (33)/ (28) 


15 


35 


Line Current, in A 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


16 


36 


Stator Power, in W 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


17 


37 


Core Loss, in W 


From 6.6.2.3 for machine 1 


From 6.6.2.3 for machine 2 


18 


38 


Stator/ 2 /? Loss, in W, at/, 


From 6.6.2.4 for machine 1 


From 6.6.2.4 for machine 2 


19 


39 


Power Across the Air Gap, in W 


(19) = (16) -(17) -(18) 


(39) = (36) + (37) + (38) 


20 


40 


Rotor/ 2 /? Loss, in W 


(20) = (19) x (12) 


(40) - (39) x (32) 


21 


41 


Friction and Windage Loss, in VV 


From 6.6.2.2 for machine 1 


From 6.6.2.2 for machine 2 


22 


42 


Total Conventional Loss, in W 


(22) = (17) + (18) + (20) + (21) 


(42) = (37) + (38) + (40) + (41) 


23 


43 


Rotor Current, in A 


For each test point using Eq. 71 


For each test point using Eq. 71 


24 


Combined Stray-Load Loss, in W 


(24) = (16) - (36)- (22) - (42) 


25 


44 


Strav-Load Loss, in W 


(25) = (20) x (24) / [(20) + (40)] 


(44) = (24) -(25) 


Part B of Test Point - Machine 1 as a generator and Machine 2 as a motor 


45 


63 


Ambient Temperature, in °C 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


46 


64 


Stator Winding Temp, t t , in °C 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


47 


65 


Frequency, in Hz 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


48 


66 


Synchronous Speed, in r/min 


(48) = 1 20 x (47) / No. of poles 


(66) = 120 x (65) / No. of poles 


49 


67 


Speed, in r/min 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


50 


68 


Slip Speed, in r/min 


From 6.6.1.3 or =(49) -(48) 


From 6.6.1.3 or = (66) ~ (67) 


51 


69 


Slip, in p.u. 


(51) = (50)/ 48) 


(69) = (68) / (66) 


52 


70 


Line-to-Line Voltage, in V 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


53 


71 


Volts / Hertz 


(53) = (52) / (47) 


(71) = (70)/ (65) 


54 


72 


Line Current, in A 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


55 


73 


Stator Power, in W 


From each test point, from 6.6.1 .3 


From each test point, from 6.6.1 .3 


56 


74 


Stator/ 2 /? Loss, in W, at t t 


From 6.6.2.4 for machine 1 


From 6.6.2.4 for machine 2 


57 


75 


Power Across the Air Gap, in W 


(57) = (55) + (17) + (56) 


(75) = (73) - (37) - (74) 



Form C2, Parti 



Copyright © 2004 IEEE. AH rights reserved. 



61 



Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



Ml 


M2 


Description 


Machine 1 


Machine 2 


57 


75 


Power Across the Air Gap. in W 


(57) = (55)+ (17) + (56) 


(75) = (73) - (37) - (74) 


58 


76 


Rotor 1 2 R Loss, in \V 


(58) = (57) x (51) 


(76) = (75) x (68) 


59 


77 


Total Conventional Loss, in W 


(59) = (17) + (21)+ (56) + (58) 


(77) = (37) + (41) + (74) + (76) 


60 


78 


Rotor Current, in A 


For each test point using Eq. 71 


For each test point using Eq. 71 


61 


Combined Stray-Load Loss, in W 


(61) = (55) -(73) -(59) -(77) 


62 


79 


Stray -Load Loss, in W 


(62) = (61) ~ (79) 


(79) = (76) x (61) /[ (58) + (76)] 


Combination of Part A and Part B Data 




Machine 1 


Machine 2 


80 


82 


Average Rotor Current, in A 


(80) = [(23) + (60)]/2 


(82) = [.(43) + (78)] / 2 


81 


83 


Average Stray-Load Loss, in W 


(81) = 1(25) + (62)J/2 


(83) =[(44) + (79)]/ 2 


Linear Regression Analysis 


Machine 1 - Intercept (84) Slope (85) Correlation Factor (86) 


Machine 2 - Intercept (87) Slope (88) Correlation Factor (89) 


Corrected Values 


90 


99 


Stator l 2 R Loss, in W, at r s 


As in (18) with R at t s 


As in (38) with R at t s 


91 


100 


Power Across Air Gap, in W 


(91) = (16) -(17) -(90) 


(100) = (36) -(37) -(99) 


92 


101 


Slip, in p.u. 


(12) Corrected as in 5.3.2 


(32) Corrected as in 5.3.2 


93 


102 


Speed, in r/min 


(93) = (9)x [1.00 -(92)] 


(102) = (29) x [1.00- (101)] 


94 


3 03 


Rotor I 2 R Loss, in W, at t s 


(94) = (93) x (92) 


(103) = (102) x (101) 


95 


104 


Stray-Load Loss, in W 


(95) = (85) x (80) 2 


(104) = (88)x(82) 2 


96 


105 


Total Loss, in W 


(96) = (90) + (94) + (95) + (17) + (21) 


(105) = (99) + (103) + (104) + (37) + 
(41) 


97 


106 


Shaft Power, in W 


(97) = (16) -(96) 


(106) = (36) -(105) 


98 


107 


Efficiency, in % 


(98)= 100 x (97) /(1 6) 


(107) = 100 x (106)/ (36) 



Parentheses, ( ), normally used with equation numbers are not used here to avoid confusion with the form item numbers. 

Summary of Characteristics 

Machine 1 [Machine 2 similar but not shown here. See Form C.J 



Load, in % of rated 


25 


50 


75 


100 


125 


150 


Power Factor, in % 














Efficiency, in % 














Speed, in r/min 














Line Current, in A 















Plot the line current, speed, and efficiency vs. output watts and then select values for these same quantities at precise load points to 
obtain the summary of characteristics. The power factor is computed for each precise load point from its amperes, volts, and input 
watts. The input power for the power factor calculation is: input power = 100 x output power from curve/efficiency in percent. 

Form C2, Part 2 



68 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



9.10 Form E-Method E-E1 



Type 

Frequency, 



_ Design _ 



Volts 



Degrees C Temperature Rise . 



_ Frame _ 



„Rating . 



_ Synchronous r/min _ 
_Time Ratine , 



_Phase_ 



_Serial No. 



Model No. 



Description (Motoring)(Generating) 


l 


2 


3 


4 


5 


6 


Ambient Temperature, in °C 














tStator Winding Temperature, t u in °C 














Frequency, in Hz 














Synchronous Speed, n s in r/min 














Observed Speed, in r/min 














Observed Slip, in r/min 














Corrected Slip, in r/min 














Coirected Speed, in r/min 














Line-to-Line Voltage, in V 














Line Current, in A 














Stator Power, in W 














Core Loss, in \V 














Winding resistance corrected to t s 














Stator I 2 R Loss, in W, at t s 














Power Across the Gap, in W 














Rotor/ 2 /? Loss, in W 














Friction and Windage Loss, in W 














Rotor Current, in A 














* Stray- Load Loss, in W 














Total Loss, in W 














Shaft Power, in W 














Efficiency, in % 














Power Factor, in % 















♦Method B see 5.7.2 or 5.7.3, Method El See 5.7.4 

U t — temperature of stator winding as determined from stator resistance or temperature detectors during test. 

Summary of Characteristics 



Load, in % of rated 


25 


50 


75 


100 


125 


150 


Power Factor, in % 














Efficiency, in % 














Speed, in r/min 














Line Current, in A 















Copyright © 2004 IEEE. All rights reserved. 



69 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



9.11 Form E2-Method E-E1 calculations 



Type 

Frequency _ 



Design _ 



. Frame _ 



.Volts . 



Degrees C Temperature Rise , 



_ Synchronous r/min _ 
Time Rating 



_Raling . 



Phase. 

Serial No. 



Model No. 



Cold Stator Winding Resistance Between Terminals (1) Ohms @ (2) °C From 6.7.1 .1 


Specified Stator Temperature, t s , (3) °C in a 25 °C Ambient, From 3.3.2 c) 


(Test)(Standard) Stray-Load Loss, (P' SL ) = (4) *in W @, /' 2 , (5) A 


Item 


Description (Motoring)(Generating) 


Source or Calculation 




6 


Ambient Temperature, in °C 


From test of 6.7. 1.2 




7 


tStator Winding Temp, t t , in °C 


From each point of test 6.7.1 .2 




8 


Frequency, in Hz 


Line frequency 




9 


Synchronous Speed, in r/min 


= 1 20 x (8) / number of poles 




10 


Observed Speed, in r/min 


From each point of test 6.7. 1 .2 




11 


Observed Slip, in p.u. 


=E(9)-(10).]/(9) 




12 


Corrected Slip, in p.u. 


(10) corrected per 5.3.2 




13 


Corrected Speed, in r/min 


U~(12)jx(9) 




14 


Line- to- Line Voltage, in V 


From each point of test 6.7.1 .2 




15 


Line Current, in A 


From each point of test 6.7.1 .2 




16 


Stator Power, in W 


From each point of test 6.7. 1 .2 




17 


Core Loss, in W 


From 6.7.2.3 




18 


Winding resistance corrected to t s 


Correct (1) per 5.2.1 




19 


Stator 1 2 R Loss, in W, at t s 


= 1.5x(15) 2 x(18) 




20 


Power Across the Gap, in W 


= (16) -(17) -(19) 




21 


Rotor l 2 R Loss, in W 


= (12)x(20) 




22 


Friction and Windage Loss, in W 


= From 6.7.2.2 




23 


Rotor Current, in A 


From Equation 23 using (15) and / 




24 


Stray-Load Loss, in W 


See 5.7.2.5 for Method E or 5.7.4 for Method El 




25 


Total Loss, in W 


= (17) + (19) + (21) + (22) + (24) 




26 


Shaft Power, in W 


For motor: = (16) -(25) 
For generator: = (16) + (25) 




27 


Efficiency, in % 


For motor: = 100 x (26) / (16) 
For generator: = 100 x (16) / (26) 




28 


Power Factor, in % 


= 100 x (16) /[1. 732 x(14)x(15)] 





T/ ; ~ temperature of stator winding as determined from stator resistance or temperature detectors during test. 
Parentheses, ( ), normally used with equation numbers are not used here to avoid confusion with the form item numbers. 



70 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 

9.12 Form F-Methods F, F1, C/F, E/F, and E1/F1 



Serial No. 

Type Rating. 



_ Voltage „ 



.Model No. . 



_ Synchronous Speed . 



IEEE 
Std 11 2-2004 



Phase 



..Frequency _ 



Description (Motoring)(Generating) 


1 


2 


3 


4 


5 


6 


A" 


Slip in p.u. 














R 2 ls 


Effective rotor resistance 














X 2 


Rotor reactance 














z? 


Rotor impedance 














G x 


Rotor conductance 














G fc 


Core conductance 














G 


Rotor & mag. circuit conductance 














-B 2 


Rotor susceptance 














-B M 


Magnetizing susceptance 














-B 


Rotor & magnetic circuit susceptance 














r 2 2 


Rotor & magnetizing circuit admittance 














R s 


Rotor & magnetic circuit resistance 














«i 


Stator resistance per phase 














R 


Total resistance 














x s 


Rotor & magnetic circuit reactance 














X\ 


Stator reactance 














X 


Total reactance 














z 


Total impedance 














'l 


Stator current 














h 


Rotor current 
















Stator power 
















Rotor power 
















Stator I 2 R loss 














Pi, 


Core loss 
















Rotor l 2 R loss 














p f 


Friction & Windage loss 














P S L 


Stray-Load loss 
















Total losses 
















Shaft power, in W 
















Efficiency in % 
















Power factor in % 
















Speed in r/min 
















Torque in N-m 










| 



Copyright © 2004 IEEE. All rights reserved. 



71 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



9.13 Form F2-Methods F, F1, C/F, E/F, and E1/F1 calculations 



Serial No. 

Type Rating _ 



. Model No. . 



.Voltage 



. Synchronous Speed „ 



. Phase . 



.Frequency . 



Before starting calculation, fill in following items, obtained from previous tests: 

R 2 = (I) V = phase volts (2) P' S L (3) at Vi (4) and n s (5) also all the items below that are 

marked with an asterisk. (n lV = synchronous speed) 


Assume a value of slip, s, corresponding to expected full -load speed for full -load point and proportional values for other loads. For 
motor operation, a- is positive. For generator operation, s is negative. Numbers in ( ) represent item numbers. 


Item 


Description (Motoring)(Generating) 


Source or Calculation 


6 


s 


Slip in p.u. 


Assume values for each load point 


7 


R 2 /s 


Effective rotor resistance 


(7) = (l)/(6) 


*8 


*2 


Rotor reactance 


From equivalent circuit, see 5.9 


9 


z 2 2 


Rotor impedance [Quantity squared] 


(9) = (7) 2 + (8) 2 


10 


Oi 


Rotor conductance 


(10) = (7)/ (9) 


*1I 


G fe 


Core conductance 


From equivalent circuit, see 5.9 


12 


G 


Rotor & magnetic circuit conductance 


(12) = (.10) + (11) 


13 


-B 2 


Rotor susceptance 


(13) -(8)/ (9) 


*14 


~B M 


Magnetizing susceptance 


From equivalent circuit, see 5.9 


\5 


-B 


Rotor & magnetic circuit susceptance 


(15) = (13) + (14) 


16 


V2 2 


Rotor & magnetizing circuit admittance [Quantity squared] 


(16) = (12) 2 + (15)2 


17 


/? ? 


Rotor & magnetic circuit resistance 


(I7) = (12)/(J6) 


*18 


*i 


Stator resistance per phase 


From tests, see 5.9 


19 


R 


Total resistance 


(19) = (17) + (18) 


20 


X * 


Rotor & magnetic circuit reactance 


(20) = (15)/ (16) 


*21 


*\ 


Stator reactance 


From equivalent circuit, see 5.9 


22 


X 


Total reactance 


(22) = (20) + (21) 


23 


z 


Total impedance 


(23) = square root of [ (1 9) 2 + (22) 2 j 


24 


h 


Stator current 


(24) = (2) / (23) 


25 


h 


Rotor current 


(25) = (24) / square root of 1(9) x (16) J 


26 




Stator power 


(26) = 3x(24) 2 x(19) 


27 




Rotor power 


(27) = 3 x (25) 2 x (7) 


28 




Stator I 2 R loss 


(28) = 3x(24) 2 x(18) 


29 


Pk 


Core loss 


(29) = 3x(24) 2 x(ll)/(l6) 


30 




Rotor 1 2 R loss 


(30) = (6) x (27) 


*31 


p f 


Friction & Windage loss 


From tests, see 9.14 


32 


PSL 


Stray-Load loss 


(32) = (3)x|.(25)/(4)] 2 


33 




Total losses 


(33) = (28) + (29) + (30) + (31) + (32) 


34 




Shaft power, in W 


(34) = (26) - (33) 


35 




Efficiency in % 


For Motoring: (35) = 1 00 x (34) / (26) 
For Generating: (35) = 100 x (26) / (34) 


36 




Power factor in % 


(36)= 100 x (19)/ (23) 


37 




Speed in r/min 


(37)=(5)x|.l-(6)J 


38 




Torque in N-m 


(38) = 9.549 x (34)/ (37) 



72 



Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 

9.14 Test and equivalent circuit results 

Serial No. 



Machine 
Type 



R aline 



Vollaee 



IEEE 
Std 112-2004 



^Synchronous Speed_ 



Model No. _ 



^Frequency _ 



_ Phases _ 



Summary of Tests 



No Load 


Line Current, / . 
in A 


Stator Power, fV 
inW 







Impedance Data by Method of 5.9. 1 


Frequency 
Hz 


Line Volts 


Line Current, /, 
in A 


Stator Power, P, 
inW 



































Constants and Summary of Equivalent Circuit Parameters 



V\ 


volts per phase 


R\ 


ohms 


R 2 


ohms 


Rfe 


ohms 


*1 


ohms 


^2 


ohms 


(X { +Xt) 


ohms 


Bm 


Siemens 


Gr, 


Siemens 


Pf 


# watts See 5.5.4. 


Pk 


#watts See 5.5.5. 


Psi 


# * watts at Ii = < 


N, 


r/min 



amperes 



*See 5.7.2, 5.7.3, or 5.7.4. 

# When used in Method F. Fl , C/F. E/F, or El/FJ tests, these quantities are for the total machine and all others are per phase. 



Copyright © 2004 IEEE. All rights reserved. 



73 



IEEE 

Std 1 1 2-2004 IEEE STANDARD TEST PROCEDURE FOR 

Annex A 

(informative) 

Bibliography 

[Bl] 1 C.FR Part 431 , Department of Energy, Office of Energy Efficiency and Renewable Energy, ''Energy 
Efficiency Program for Certain Commercial and Industrial Equipment: Test Procedures, Labeling, and Cer- 
tification Requirements, for Electric Motors, Einal Rule," Federal Register, Vol. 64, No. 192, pp 54114- 
54172, October 5, 1999. 

[B2] API Std 541 , 4th Edition: Form- Wound Squirrel Cage Induction Motors— 500 Horsepower and Larger, 
2003. 

[B3] I'EC 60034-9: Rotating Electrical Machines-Part 9: Noise Limits, 1997. 

[B4J IEC 60034-14: Rotating Electrical Machines— Part 14: Mechanical vibration of certain machines with 
shaft heights 56mm and higher— Measurement, evaluation and limits of vibration, 1996. 

|B5] IEEE Std 1 ,M -1 986, IEEE Standard General Principles for Temperature Limits in the Rating of Electric 
Equipment and for the Evaluation of Electrical Insulation. 

[B6] IEEE Std 4™ -1995 Standard Techniques for High-Voltage Testing. 

[B7] NEMA MG-1 -2003, Motors and Generators. 

[B8] NIST Handbook 1 50-10, Efficiency of Electric Motors, (EEM). 



74 Copyright © 2004 IEEE. All rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



Annex B 



(informative) 



Typical report of test form for routine tests 



Name of Manufacturer,. 



Address of Manufacturer _ 



Purchaser , 



Date of Test _ 



Manufacturer's Order No. 
Purchaser's Order No. 



Nameplate Data 



Rated 
hp/kW 


Service 
Factor 


Rated Speed 
r/min 


Phase 


Frequency 
Hz 


Volts 


Amperes 

















Type 


Frame 


/Temp Rise^ 

by method 

\ Indicated / 




/Ambient temp\ 
and Insulation 

\ Class ) 




Time 
Rating 


Design 

Letter 


Code Letter 

for Locked 

kVA/hp 















Test Characteristics 



Serial 

No. 


No Load 


Locked Rotor 


Wound 
Rotor 
Open- 

Circuit 

Voltage 


High 
Poten- 
tial 
Test 

Voltage 


Stator Winding 

Resistance 

Between 

Terminals 


Volts 


Fre- 
quency 
Hz 


Speed 
r/min 


Am- 
peres 


Kilo- 
watts'* 


Volts 


Fre- 
quency 
Hz " 


Am- 
peres 


Kilo- 
watts* 




Ohms 


Temp 
in 
°C 





















































































































































































































*If measured, optional. 

Notes: 



Data on test from _ 



_machine 



Approved by _ 



Date„ 



(this or duplicate) 



Copyright © 2004 IEEE. All rights reserved. 



75 



IEEE 

Std 112-2004 



Annex C 

(informative) 



Typical report of test form 



Name of Manufacturer _ 



Address of Manufacturer _ 
Serial No. 



Model Number.. 



IEEE STANDARD TEST PROCEDURE FOR 



Manufacturer's Order No. 
Date of Test 



Purchaser's Order No. _ 
Purchaser 



Nameplate Rating 


Rated 

hp/kW 


Service 

Factor 


Rated Speed 
r/min 


Phase 


Frequency 
Hz 


Volts 


Amperes 


Type 


Frame 




















Temperature Rise 


Conditions of Test 


Temperature Rise °C 










Stator 


Rotor 
















Windings 




Windings 






Hours 
Run 


Line 
Volts 


Line 
Amperes 


Cooling 
Air/C 




*By 

Method 




*By 
Method 


























Characteristics 


Rated Slip 

percent 


No-Load Line 
Current, amperes 


Secondary Volts 
at Standstill 


Secondary Amperes per 
Ring at Rated Load 


Resistance at 25 °C 
(between lines), ohms 










Prim 










Sec 


Torque and Starting Torque 




High Potential Tests 


Break-Down Torque 
in # 


Locked- Rotor Torque 

in # 


Starting Current 
Amperes (locked rotor) 


Volts ac for Sec. 


with % volts applied 


with % volts applied 


with % volts applied 


Stator 


Rotor 













Efficiencies and Power Factor 



Efficiency, Percent 


Power Factor, Percent 


Rated Load 


75% Load 


50% Load 


Rated Load 


75%; Load 


50% Load 















* Indicate method as; Thermometer, Thermocouple, Resistance, or Embedded Detector. # Indicate units: N-m or lbf-ft 

Notes: 



Data on test from 



(this or duplicate) 



. machine Approved by „ 



Date 



76 



Copyright © 2004 IEEE. All rights reserved. 



IEEE 
POLYPHASE INDUCTION MOTORS AND GENERATORS Std 1 1 2-2004 

Annex D 

(informative) 

Units of measure 
D.1 Units of measure 

This standard uses metric units of measure in accordance with IEEE standard policy. However, this standard 
can be used when the units of measure are horsepower, hp, for shaft power, pound-force-feet, lbf-ft, for the 
torque(s) and pound-feet2, lb-ft2, for inertia. The areas in the specification that need to be modified when 
using these customary units and the specific modifications required are covered in D.1.1 through D.l .5. 

D.1.1 Mechanical power 
D. 1.1.1 Load test 

The mechanical power in the load test as calculated in 5.6.1 .1 is in watts. With the shaft torque, T, being 
measured in lbf-ft instead of N-m, the k 2 factor in Equation (10) is 7.043 instead of 9.549. See D.l .2.1 . 

D.1.1. 2 Output power 

The output power of a motor (input power of a generator) can be presented in horsepower by simple conver- 
sion of the calculated corrected stator power of the test forms. This power value as calculated is in watts. 
Divide this calculated power by 745.7 and the resulting number is the output power in hp. See Table D.l . 

D. 1.2 Torque 

D. 1.2.1 Shaft torque 

The shaft torque used in the mechanical power calculation of D.l .1 .1 is obtained from Equation (1 1 ), which 
starts with the measured shaft torque and applies a dynamometer correction factor, if this correction is 
needed. Equation (11) is valid for either unit of torque measure as long as all torques values use the same 
units of measure. Using mixed units of measure will always give wrong results and will invalidate the test. 

D. 1.2.2 Dynamometer correction 

The dynamometer correction is calculated as in 5.6.1.2 using Equation (12). The dynamometer correction 
torque, in lbf-ft, To, is calculated using Equation (12) with k 2 equal to 7.043 and with T A measured in lbf-ft. 

D.1.2.3 Locked-rotor torque 

See 7.2.2. The locked-rotor torque can be calculated using Equation (77). Change the value of factor ko to 
7.043 and the result of solving Equation (77) will be the maximum locked-rotor torque in lbf-ft. 

D. 1.2.4 Speed-torque curve — Method 1 

See 7.3.2.1 . The torque at each load point can be calculated using Equation (78). Change the value of factor 
k2 to 7,043 and the result of solving Equation (78) will be the torque in lbf-ft. 



Copyright © 2004 IEEE. All rights reserved. 



77 



IEEE 

Std 112-2004 



IEEE STANDARD TEST PROCEDURE FOR 



D.1.2.5 Speed-torque curve— Method 2 

See 7.3.2.2. As in D.l .2.5, the torque at each load point can be calculated using Equation (79). However, the 
moment of inertia must be in Ib-ft 2 . With this and changing the value of factor hi to 7.043, the result of solv- 
ing Equation (79) will be the torque in lbf-ft. 

D. 1.2.6 Speed-torque curve-Method 3 

See 7.3.2.3. The torque at each load point can be calculated using Equation (80). Change the value of factor 
kj to 7.043 and use values of motor friction and windage torque, Tf w , in lbf-ft. Solve Equation (80) for each 
speed point and the resulting values will be the torque, T, measured in lbf-ft. 

D.1.3 Test forms 

When using customary units, the test forms of Clause 9. should be modified to show the correct units of 
measure, lbf-ft for torque and hp for shaft power, to add additional lines to show shaft power in hp and to 
show the correct ki factor in applicable calculations. The changes needed are shown in Table D.l . 

Table D.1— Form changes required 



Subclause 


Form l.D. 


Units are: 


Item No. 


Add line 
after No. 


Add on new line 


Calculation 


9.2,9.3 


A,A1 


lbf-ft 


14,15,16 


- 


- 


- 


- 


17 


— 


- 


*(17) = (16)x(13)/7.043 


- 


- 


26 


Shaft Power, in hp | =(17)/ 745.7 


9.4,9.5 


B,B2 


lbf-ft 




- 


___ 


■ 




- 


1 * (27) = (26) x (12)/ 7.043 


- 




43 


Shaft Power, in hp [ =(41)/ 745.7 


9.6,9.7 


Bl,B1-2 


lbf-ft 






- 


- 


- 


23 




- 


* (23) = (22) x (8)/ 7.043 


- 


- 


39 


Shaft Power, in hp 


= (37)/ 745.7 


9.8,9.9 


C,C2 


- 


- 


98 


Shaft Power, in hp 


= (97)/ 7457 


- 


- 


107 


Shaft Power, in hp 


= (106)/ 7457 


9.10,9.11 


E,E2 


- 


- 


28 


Shaft Power, in hp | =(26)/ 745 .7 


9.12,9.13 


F,F1 


- 


— 


38 


Shaft Power, in hp | =(34)/ 745.7 



* These calculations are basically unchanged, only the constant has changed because of the use of lbf-ft units for the 
shaft torque. 

NOTE— The "new line" for the test forms shown in Table D.l , is for recording the shaft power in horsepower. These 
lines are introduced at the bottom of the forms so the Item Numbers that show calculations are not compromised. On the 
actual test form, this new line could appear directly after the existing "Shaft Power, in W" listing, if desired. 

D.1.4 Assumed stray-load loss 

The stray-load loss to be used with machines being tested by Efficiency Test Methods El , Fl or El/FI is 
selected from Table D.2 based on the rated horsepower. 



78 



Copyright © 2004 IEEE. Ali rights reserved. 



POLYPHASE INDUCTION MOTORS AND GENERATORS 



IEEE 
Std 112-2004 



Table D.2— Assumed values for stray-load loss 



Machine rating 
In hp 


Stray-load loss 
percent of rated load 


1-125 


i .8% 


126-500 


1.5% 


501-2499 

i 


1.2% 


1 2500 
and greater 


0.9% 



The value of stray-load loss at rated load [F S l in Equation (22)] , in watts, is equal to the product of the per- 
cent value of stray-load loss in Table D.2, the rated hp, and the conversion factor 745.7 divided by 100. 

D.1.5 Resistance reading at shutdown 

Table D.3 shows the maximum permitted time between shutting off the power on the temperature test and 
obtaining the first stator resistance reading. The maximum delay is selected from Table D.3 based on the 
machine horsepower rating. 



Table D.3— Maximum time delay in resistance measurements 



Machine rating 
in hp 


Time delay after switching 
off power (seconds) 


50 or less 


30 


Above 50 to 200 


90 


Above 200 


120 



Copyright © 2004 IEEE. All rights reserved. 



79